rss2atom?

Does anyone know of some code or command line utility that converts RSS
flavors to Atom 1.0? I could have sworn that I bookmarked some utility to
do this, but I can't find it, and web searches only turn up the tnl.net
service, which seems to throw some parts out.

If I don't find something, I'll probably write something in XSLT, but I
thought I'd try the lazy route first...

thanks,

Bob