Trying to import or include an external XSL stylesheet from an embedded one fails. This is an edge case issue - there's little reason to use embedded stylesheets if one is going to import an external one anyway. Other browsers also seem buggy, but command-line xsltproc handles this test case just fine.
Created attachment 17467 [details] test case
*** Bug 35039 has been marked as a duplicate of this bug. ***
Given that this is a problem on http://www.weather.gov/, I'd say it just got a bit more interesting :-)