The digital rights management in particular is completely dependent on the 2003 rights server. An interesting point is that the rights server has to be exposed to the Internet or recipients of protected documents and emails will not be able to read them. Expect this to be a convenient entry point for more worms and exploits.

The colaboration features also depend on Windows 2003 server and some "value add" server applications. I suspect they're building a structure so complex and intertwined it'll develop a reputation for disrupting business due to obscure "this behavior is by design" problems, outright failures and the inability of many organizations to administer it. Costs they will be arising.