Froyo (Android OS 2.2) installs the official Android Twiter client as part of the overall platform update. But, quite honestly, I don’t like the official Twitter client and plan to continue to use Seesmic for Android.
Unfortunately, some Nexus One users have reported problems with Seesmic after upgrading to Froyo. Fortunately, Seemsic has a patched version 1.3.1 in the Android Market.
So, if you updated your Nexus One to Android OS 2.2 and are a Seesmic users, tap on the Market app and update the app.