Thought that headline would catch your eye. Most times, an x.x.1 update might seem not worth bothering with. But if you're using the HP PhotoSmart R607 camera, you ought to grab this one now. Or within Lightroom 3, you can choose Help > Check for Updates; in Photoshop CS5 it's Help > Updates.
The reason: A bug introduced in the April 29 releases of Lightroom 3.4 and Camera Raw 6.4 can corrupt photos shot with the now discontinued R607—at least in a few cases. (Adobe's May 19 alert explains the nitty-gritty.)
If that's not your camera, you can rest easy. If you're using a Canon Rebel T3i, Nikon D5100 or Fuji FinePix X100, the update includes new support for those models. For the rest of us, it's reassuring that Adobe rolled out the fix less than a week after the alert.