As you are probably aware, the Google XML Sitemaps plugin is not yet compatible with Multi-Site (There is a version working through beta testing right now but it has its own problems.)
Since that plugin doesn't work with Multi-Site, we decided to give Simple Sitemaps a try.
Here is an example of the error:
XML parsing failed
XML parsing failed: syntax error (Line: 129, Character: 76)
Reparse document as HTML
well-formedness constraint: entity declared
I'm wondering if there's any suggested work-around to handle this?