The US Patent and Trademark Office tentatively invalidated Apple's so-called rubber-banding patent back in October, and it looks like it's now done so again with one of the company's key multitouch-related patents. According to FOSS Patents, the USPTO has issued an Office Action rejecting all 20 claims of patent 7,479,949, which is specifically related to scrolling and is described as "Touch screen device, method, and graphical user interface for determining commands by applying heuristics." Unlike the rubber-banding patent, though, this one did not figure in Apple's recent trial with Samsung, although it has been used in cases against Motorola and HTC.
Update: To be clear, this is just the first step of the patent's re-examination and Apple gets to respond to each of the issues raised by the USPTO. So, invalidation of all (or any) of the claims is far from assured.