I haven't checked this for myself yet but, tonight I noticed that Justin Rogers has posted an interesting entry relating to an implementation detail of .NET Regex matching:

http://weblogs.asp.net/justin_rogers/archive/2004/02/13/72800.aspx

I'm not really sure whether I'd ever be in a position to take advantage of this new knowledge - but, it's an interesting titbit all the same.

Rotor code for Match and MatchSparse - http://dotnet.di.unipi.it/Content/sscli/docs/doxygen/fx/bcl/regexmatch_8cs-source.html

Thanks Justin :-)