Seesmic has announced the launch of Twitter apps for Android and BlackBerry handsets, to complement its existing desktop and web clients.

The apps are available now, and allow Twitter users to monitor and post from multiple Twitter accounts, as well as searching Twitter.

The BlackBerry version also supports geo-location tweets, showing a user's current location to the world, as well as the new Twitter lists - which let users create lists of other Twitterers around themes.

Seesmic is also working on an iPhone app, according to TechCrunch, although for once, it's following the BlackBerry and Android versions.

There is plenty of competition already on these smartphones' app stores, but Seesmic's desktop client has a lot of fans, so the new mobile versions should get a running start.