IDA Pro engine updates are not so interesting as HexRays plugin updates. It's hard to implement something completely new in dissassembler itself (however dockable windows should be nice I suppose). But decompiler has a huge potential. For example Ilfak wrote Hex-Rays can now decomple floating point:
http://hexblog.com/2009/05/decompiling_floating_point.html#more
Unfortunately the only HexRays version I saw in public was HexRays 1.0, and it was somewhat limited in functionality and usablitily (but quite impressing).
BTW, I reaploaded HexRays 1.0 to FTP server.