This is big news, and no mistake (as treebeard used to say), Sun and Microsoft buried the hatchet and agreed to cooperate for the next ten years.
I think this is a really good news for technology (though I expect people will complain as usual): they agreed to collaborate technically to help interop between Java and .NET. I hope this is just a sign that the rumors of a possible port of Java to Microsoft CLR will be true. It would be great being able to integrate Java (and Java programs) with C#, VB and all the other languages in a seamless way.
One of the reasons because I moved from Java development was the lack of interoperability that was forcing me writing and using only Java: I like programming different languages! This is why I liked COM/CORBA and now far more .NET.