Conclusion

.NET is definitely an improvement over Java framework, but it is NOT going to displace Java any time soon. Though in coming years Java and .NET will converge.
It currently lacks support for other platforms. Since .NET has been architected by Microsoft, it is less likely  to find the open source support base of free thinking programmers, which was one of the main reasons of Java's popularity.
Java has been there for more than five years now, and Java programmers have already survived two waves of downturn. First in 1998 when most web sites weeded out Applets and second in late 2000, when all the VC fueled DOTCOM hot balloons came down. Scott Adams' Dilbert strips at http://www.dilbert.com has a good fill of VC and DOTCOM cartoons.
All remaining employed Java programmers must have a good handle of .NET architecture to continue to remain employable.
The party is over for DOTCOM, so let's party with DOTNET !!!