When your email accounts, calendar, and address book — essentially all the programs that comprise your online life — are in one place like Comcast, you’ll be less likely to switch to another ISP.

This makes a lot of good business sense for Comcast, though it seems to make less sense for the consumer, but maybe this is where Plaxo’s address book comes in. Nonetheless, Plaxo can sync your address book and calendar, but it can’t sync your emails.

The scale of Comcast probably makes them either interesting or threatening to the “big guys” - one obstacle they may need to elegantly overcome is getting people to switch to their Comcast account as their anchor email for those subscribers who are already using GMail, Yahoo Mail, etc. The key will be an easy switching process and excellent functional capability - I’ll be interested to see how this progresses.

On a related note, I understand HP is running Tripwire on the email servers to keep the up and stable. A good move.