DP Review reviews Lightroom 3.
Money quote: ”It’s not much of an exaggeration to say that at high ISO settings, switching to the new RAW processing engine is like switching to a new camera.” I agree, wholeheartedly. The output from LR3 from my 50D is exponentially better than from LR2. If you’re using LR2, and have an APS-C sensor, take my advice, download the trial of LR3, and see for yourself (if you’re chary of purchase).
Comments:
My update process created a duplicate catalog, and when I open files that have been LR2 processed, there’s a small delay while re-rezzing the image, and a small exclamation point button shows up on the bottom right. DO NOT UPDATE ALL YOUR FILES AT ONCE. It’ll ask if it can do your entire filmstrip. The development settings are different. I did this on an important filmstrip, and the whole batch processed significantly lighter. Go at it one at a time, until the processing differences are clear.
Next entry: AETuts+: 31 Absolutely Spectacular VFX Breakdowns. >>

I still have LR2, I’m guessing you need to reimport the RAW files to get the new processing, right?