<p>I'm writing some xlst file which I want to use under linux and Windows. 
In this file I use node-set function which declared in different namespaces for MSXML and xsltproc ("urn:schemas-microsoft-com:xslt" and "<a href="http://exslt.org/common" rel="nofollow noreferrer">http://exslt.org/common</a>" respectively). Is there any platform independent way of using node-set?</p>

Firefox 3 implements node-set (as part of the EXSLT 2.0 namespace improvements) in it's client-side XSLT processing.
Maybe not quite the answer you were looking for - but it could be, depending on the context of your problem. ;-)