I have been using Google Scholar as one of my main sources for finding academic papers and books, and find that is has improved considerably over the last few years.
A while ago they also opened for creating your own academic profile. It is fairly basic, but they have done a great job in managing to find most of my papers, citations, etc.
Now also Microsoft has jumped on academic search, and has launched their own service. When I first visited my personal page, they had only found a handful of my publications. Differently to Google Scholar, though, they allow people to upload their own BibTeX files with publication information. The data from the BibTeX file is not used directly, but somehow merged with everything else. The end result is not so bad, and after my upload the content on my profile has improved considerably.
Perhaps more interestingly than the profile page, though, are some of the new visualisation tools they offer, including a co-author graph that neatly visualises who I have published together with.
The citation graph shows who has been citing my stuff, which can potentially also be interesting to know.
There is also a co-author path, in which it is possible to see the connections between yourself and some other person. This is not directly useful, but can potentially be amusing, I guess.
All in all, the new MS Academic Search seems promising, and with some interesting features that make it stand out from Google Scholar.