Adobe has released a public beat of Lightroom 4 onto Adobe labs. The full press release is on the Wetpixel front page here:
http://wetpixel.com/i.php/full/adobe-relea...ghtroom-4-beta/
But I have already found a couple of very cool features. The huge one is local color temperature (white balance) adjustment. Finally, you can correct weird color cast locally, rather than having to duplicate layers and mask in PS. The noise algorithm has been tweaked again, and seems better, and I think the sharpening too. The clarity slider's effects seem more marked. I haven't tried printing yet, but I am going to guess that the soft proofing feature is going to be good.
It is still missing any form of layers type editing.
Being able to export directly to email is great too (I know you could do it before, but it was a work-around)
Adam