I do my fair share of Microsoft bashing, but I use their products when I think they are the best for the job (coincidently I am trying out Live Writer to make this post). I so far haven't had any great personal reaction to the idea of them buying Yahoo, in fact as long as they don't roger flickr senseless I don't really care. However I am genuinely happy that they along with Google, IBM, Yahoo and VeriSign have joined the OpenID Foundation. I love the idea behind OpenID, a transparent system of passing trust relationships round the internet without exposing any of your credentials; contrast it with the looks more like phishing than phishing itself approach of 3-D Secure (I know that in the not previously authorised flow for OpenID they are very similar but the fact that you can be already logged in by going to the URL you know with OpenID is the important difference). Companies like Microsoft, IBM and VeriSign have a lot of weight with serious thinking men who will look at this kind of technology and compare it with everything else they are running. Microsoft also offers a section of the young non-geek market with their messenger and hotmail accounts that this sort of concept needs to really make it.
The only real surprise with the current assault on everything open is that Sun isn't on this list.