This is a little behind the 8-ball and it's entirely possible that by the time you read this, the Lightroom update may have already been made available to the public. However, if you haven't heard, Adobe has the first update to Lightroom 4 availble to download and try as a "release candidate" meaning it's being further tested before being given the green light.
To everyone's relief, the update addresses the Point Curve adjustment bug and also tweaks some of the performance issues that were being reported in the Development Module. I've not yet loaded it myself and am waiting for the official version, but reading through some of the comments on the Lightroom blog page, it seems promising.
Have you applied the 4.1 update? What has been your experience?