Extending XSLT
Yesterday I commented about XQuery moving forward in favor of XPath 1.0 and XSLT 1.0. Whether this is a good thing or not, Oleg Tkachenko has written a fine article concerning the XPath and XSLT extension, provided by the EXSLT.NET library.
http://weblogs.asp.net/pgielens/archive/2004/08/17/215547.aspx