Actually, let me rephrase that - it seems that one can now have a Google Account / identity which isn't *@googlemail.com or *@gmail.com.
The Google Account sign up page still offers the standard Gmail option but now also includes alternative email providers including AolMail, Windows Live Hotmail, Yahoo! Mail, and others.
Everything looked the same, only my Google Account at the top right revealed that I was actually signed in as @live.com and not my standard @gmail.com account. I'd created a new Google Account with my Windows Live account!
Not sure if this was just limited to Google Docs, I then tried out the other Google services like Mail, Calendar, and Sites, which all revealed interesting results...
It would appear that choosing a Gmail.com account will give you a full-on Gmail address as your Google Account primary username but it won't replace your @live.com address. Not sure, but that's how I interpret it.
Google Calendar works fine with the @live.com account which is encouraging because it means if you prefer to stick with an alternate provider you can still make use of the Google Calendar functionality (and likewise, add Google Calendar events from shared calendars to your mobile phone without needing to have a Gmail.com account). This holds massive potential in my humble opinion, especially for businesses and organisations that want to operate with public shared calendars that offer free SMS reminders. The layered approach to shared calendars in Google Calendar, along with its free SMS reminder service, is unbeatable at the moment. Again, just my opinion :)
Google Sites also seems to let you keep your current account and create Google-hosted websites. Rejoicing there was much thereof.
Overall, this may not seem like newsworthy information for most people but it signals the start of a new era in online identity. I can already see the massive potential in Google allowing Google Accounts to not be limited to @gmail.com addresses (apart from the Gmail service, which for obvious reasons, requires you to have a @gmail.com address). Specifically of interest to me is the potential for the Google Calendar functionality. I can now share a calendar for, say, gaming events and anyone else interested in being notified of these events can sign up to my calendar without needing a @gmail.com account. In the past in order to share in my calendar with the SMS reminders you'd need a @gmail.com account but now anyone from any email provider can partake of my Google Calendar notifications without shifting email accounts. This is something that organisations, like for example a church, can harness to have their members sign up for their various calendars and layer the ones they want to keep track of. Huge potential.