Thanks Emil for pointing out that the Windows 7 Engineering blog has gone live. Its authors include Steven Sinofsky is in charge of the Windows and Windows Live Engineering Group and Jon DeVaan heads the Windows Core Operating System Division. There have been 2 posts on the blog and they don"t include any useful info.
So far Microsoft has been very tight lipped over Windows 7 and what were likely to expect from Vista"s successor. There have been a few hints with the leaking of Windows 7 M1 build in January Microsoft also said there will be some sessions at this years PDC Event covering Windows 7