first@last.us (sent by first.last@gmail.com)
Clearly not desirable, and in my case, unacceptable. I actually switched from the GMail webapp to multiple accounts in Mail.app for this reason alone. I miss the webapp, though.http://mail.google.com/support/bin/answer.py?hl=en&ctx=m...
(Click "I'm a Gmail or Google Apps user sending from an external address", then search for "on behalf of".)
The labeling feature, instantaneous syncing to my phone, search, etc... all the reasons gmail rocks, but now for all of my email. My mail is auto labeled when it is pulled through POP so I still know what account it was sent to, plus I'm already feeling way more on top of my inbox because I keep my email color labeled by project, etc. Sooooo nice.
The Android Gmail app sync is so fast that it gets to my phone before the browser extension tells me I have mail.
This is terrible for Youtube (which isn't compatible with Multiple Sign on).
These new transitioned accounts are a complete disaster for existing users who have been using Google services. You can't merge your accounts at all, so plan on managing multiple accounts. It's sad too because the existing users were the ones who cried out for help on Google's forums. Existing users are the ones with the problems that need to be solved. Unfortunately these new transitioned Apps account do nothing for us...