In this case though it seems about right - I'm a total Google fanboy but as an Apps user I'm just not allowed to use their biggest new product!
With a decent IMAP or exchange client, you can easily browse multiple mailboxes. In fact, multiple emails is probably the best reason to use a non-browser app for email.
I'm sure there are a lot of good programs I'm missing, but (from a Debian-user's perspective) nothing is worth that sort of hassle.
The mobile market still seems bent on packaging users as the commodity. First holding them ransom to carriers (remember when people had to pay for new ringtones?!) and now to app-store dealers. Nobody makes the phone they really want to use, they make the phone they can best monetize.