Server 2008 U+FFFD behavior for unknown or illegal UTF-8 sequences.
In my post Change to Unicode Encoding for Unicode 5.0 conformance I mentioned that the behavior of illegal characters has changed for Unicode 5 conformance in Windows Vista / .Net 2.0+. Those changes have also been inherited by Server 2008.
Also check out my collection of code page related articles at Code Pages, Unicode & Encodings
