We've always liked the free Seesmic Twitter app for the desktop (Windows | Mac), but one of our biggest complaints when Seesmic crossed over to the mobile world has been the Twitter client's lack of support for multiple accounts. This is no longer an issue, a Thursday night update to Seesmic for Android now makes it possible to manage more than one Twitter persona.
We tried out Seesmic's latest version, 1.2, on Google's Nexus One. Logging into one account was easy, but adding a second (or third, or hundredth) account takes an extra step of pulling up the Options menu (the soft key to the right of the back arrow on the Nexus One; a hard Menu key on various other handsets) and clicking "Add account." You can make any account your default, and can skip between accounts from the Options menu.
The logic of multiple accounts also rears up when you post an update. You'll post to the account from which you're composing by default, but tap a button to cross-post your update to any other account.
Seesmic has thrown in a handful of other changes as well. Our favorite is Seesmic's status composer auto-correcting and auto-capitalizing sentences. The app also picks up in the time line where you left off and fixes several bugs. So far, the updated Seesmic looks and acts slick on the Nexus One, though an option button on the interface could make switching between active accounts even smoother than going through the menu.