Available for download: http://labs.adobe.com/technologies/lightroom4/

My question to those who've used beta versions before: I was going to buy LR3 (have been using the trial for a couple weeks) until this news came out. Should I just download this and wait to purchase until the official 4 is released, or is it worth it to buy LR 3 and then upgrade?

I don't see how the pricing would be any different.  I would lean towards using the beta (get used to it now so you won't have to adjust after using 3 - not sure how different it will be) now and just pay for the full version once released.

LR3 is the bomb though. Can't believe I'm saying that since I've only switched to it 6 months ago!

I didn't know it came out! Yay!

I would use the beta and wait.  It can be a pain to migrate your library to the new version.  Some people have real trouble doing that.