While I'm still enjoying (and learning!) Lightroom 2, version 3 is already in the making. A public beta has been made available by Adobe, Jeffrey Friedl told in his blog a few days ago. It should allow easier publishing of collections, rather than through plug-ins (although Friedl has already updated his for LR3!), but also export of slideshows.
At least as important may be the promises of still better handling of imported pictures: for instance reduced noise. (That is one my my issues with my Sony A700 camera, so I'm going to download LR3-beta for testing!) But also the opposite: film grain effects.