Its not a matter of being locked to Exchange, as it is of being the best solution for our specific circumstances.

For us, Where we currently have a small team, with no dedicated IT support having a hosted exchange service, which provides us with Exchange, Push Mail, Sharepoint, Fax to Mail, backup, etc makes sense.

We looked at Google Apps as a possible solution, but found that it didn’t do everything we needed it to do.

As for Windows Mobile, I have to disagree with you about WM. While I currently have a personal iPhone, I’ve been using WM phones for years, and still use one pretty regularly. While the interface on does look and feel chunky, compared to iPhone OS or android, what it does, namely integration with Exchange it does very well.

And the ability to add third party apps to do some specific things is something I really miss currently.
I’m looking at getting the HTC snap once WM 6.5 comes out as its definitely looking like a very nice messaging phone.

We’re planning to get Smartphone’s for a Project team at work I’m looking at which one to get. As we are outside the US, We’re going to be looking at unlocked GSM options

As we are heavily reliant on exchange for keeping in contact and everything in sync we’ve been leaning toward WM, as while its not the latest and greatest, it’s stable and something we’ve had experience with.

However Android, and the new phones like the Hero look like a potential option depending on how stable and easy it is to use (Important for people new to smartphones) and how well it integrates with exchange.