If you are a developer, you will want to fire up SDK Manager right now and perform an update. Besides the Honeycomb SDK preview that we'll talk about separately, Google also unleashed the next version of Android Development Tools, or simply ADT, for Eclipse as well as SDK Tools r9. I've been using ADT versions 9.0.0 preview 1, 2, and 3 for a number of weeks now, and I can tell you that 9.0.0 is a huge step up to where a serious set of development tools needs to be.
Numerous improvements to the Visual Layout Editor, "go to declaration" hyperlink support for quicker navigation around declarations, near-instant AVD restarts (holy crap!!!