It’s a good bet that the average user probably doesn’t know anything about the extensions yet. We’ve compiled a list of 25 of our favorites, but Apple’s gallery will open up extensions to a wider audience, much like its downloads page did for third-party Mac OS X apps.

If you are a developer, submitting your extension is fairly simple. Apple has a form to fill out in the Safari Dev Center, and it’ll send an email to let you know when you’re extension has been received. When we walked through the submission process, Apple sent us this email:

“Thank you for submitting your Safari Extension.

Apple reviews all submissions and reserves the right to omit, edit, or reject any submission. Please note you will not receive any further notifications.

We appreciate your interest in Safari.”

Based on this reply it seems like the extensions Gallery may be subject to the same approval process as the App Store. Firefox has a similar review process for hosting addons at addons.mozilla.org, similar that is in that there is a process. Mozilla has been handling extensions for a long time, and has the process finely tuned. When submitting an addon for Firefox, the addon is available immediately and labeled “experimental,” and requires the user to acknowledge and accept the risk of using an addon that has not been reviewed by an editor. Mozilla has clear rules about what is acceptable and what is not, and has a page that addresses the review process directly. So far, I have not found the same for Safari.

Google Chrome also has extensions, but in a much looser, less controlled environment than Firefox or Safari. According to Google:

Most extensions won’t go through an approval process before being listed in the gallery. The exception to this rule are extensions which utilize the NPAPI interface, or extensions which access file:// URLs

Google’s rules are loose, but at least they are not vague. I hope that as development on Safari progresses, and the extensions gallery matures, the rules defining what is allowed and what is not are more clearly defined.

If you are interested in developing your own Safari extension, check out our beginner tutorial which walks you through creating a very basic “Hello World” extension.

On the support page created to describe the problem and the resulting warranty extension, Apple doesn’t mention which brand of hard drives are affected by name, which could mean that the problem doesn’t lie with the hard drives themselves, but with some other system components. Another indication that this is indeed the case is that all capacities of hard drive are also affected.

If you’re wondering whether or not you have an affected unit (Apple says only a “small percentage” of users will experience problems), it’s very easy to identify. Your MacBook will just stop working altogether, and any attempts to boot it will result in a screen that displays a folder icon with a question mark over top of it, as in the image below. As someone who’s seen this screen many times while fixing up old PowerBooks, I can tell you it isn’t a heartening experience.

Apple describes what you should do if you’re greeted with such a screen:

Please take your MacBook to the Apple representative most convenient for you:

• Apple Authorized Service Provider – Find one here.
• Apple Retail Store – Set up an appointment with a Genius.

If Apple or an Apple Authorized Service Provider confirms that your hard drive is affected, Apple will replace it with a new hard drive. You will need to have the original OS installation discs that were shipped with your product in order to re-install your operating system, other applications, and any backed up data.

If you need assistance finding the best service option in your area, you may contact Apple Technical Support for more information.

It sounds like any data you may have stored on the drive will be irrevocably lost if this does happen to you, so if you have one of the affected models and you haven’t yet implemented any kind of backup system, you should probably consider doing so.

If your machine has already had this problem, and you’ve already paid out of pocket to get it fixed or replace your drive, you can contact Apple Technical Support and inquire about a reimbursement process. No word on whether that extends to at home HD replacements, which is how I would’ve tried to solve the problem, but if you haven’t kept your old faulty drive, I highly doubt it would. Mostly I expect this will apply when people have taken their machines through official Apple repair channels to correct the problem.

The extension period covers affected Macs three years from the date of purchase, for this specific problem alone, or until August 15, 2010, whichever comes last, so you still have about six months in which your HD can fail and you’ll still be covered. It may seem like an arbitrary window, but Apple does include a caveat that it will be evaluating the repair need on an ongoing basis and extend that deadline if circumstances require.

Anyone experienced the symptoms Apple is describing with this model MacBook?

AT&T President Randall Stephenson hopefully has a few things up his sleeve for moving AT&T out of the dying landline business and increasingly toward the much more lucrative and future-proof mobile wireless market. Clearly, securing iPhone carrier exclusivity would be high among his goals then, since 4.3M iPhone subscribers joined up in the second half of 2008, nearly half of whom were new to AT&T.

Problem is, from where I’m standing, AT&T probably isn’t in a very good bargaining position at the moment. Sure, they’re building out their network as fast as they can to keep up with the additional strain put on their 3G network by iPhone demand, but what kind of carrot could they possibly wave in front of Apple to really convince them that selling their phone to more people on multiple networks isn’t the better deal?

The answer is money. They could offer Apple a revenue sharing model that is extremely generous, and subsidize upcoming handsets to the point where Apple could potentially offer the iPhone at a lower price point and expand their user-base even more. The key ingredient will be network buildout, though, since Apple is unlikely to stick around if AT&T can’t get its act together enough to even allow for more subscribers, regardless of how either company intends to attract them. That’s good news for current subscribers, because it means they should see significant improvements in service through at least 2011.

Related research and analysis from GigaOM Pro:
Subscriber content. Sign up for a free trial.

• Mobile Q4: All Eyes Were on Android, 4G and the Rising Tablet Tide
• Report: A Mobile Video Market Overview
• In Q3, the Tablet and 4G Were the Big Stories