There’s a nice, long summary of most of the news regarding Windows 7 here, but if you’re following it at all, only a few things will be new. For instance, there’s a session on GPU acceleration for applications, which is news to me, and although there are no specifics yet, things like CUDA and OpenCL are ripe for exploitation for a new OS looking to seem faster.
Among the promises made for Windows 7 are new desktop elements, more efficient background processes, and of course multi-touch. The other side of the coin is that the OS has transformed from the truly different OS we’d hoped for a year ago built from the ground up, to what you see: “Vista, but a lot better.” That’s not change we can believe in.
The take-home message (lacking any serious new info before these PDC sessions go public) is that 7 is being touted simultaneously (whether disingenuously or not) as both a “major release” and a continuation of Vista. How it can be both these things is beyond me, but there you have it.
Update: Some more info here.