[wladimir]

But why XML? IMO the doxygen / javadoc style of comments makes for much less pollution. XML is not a good format for text that is to be read by humans.

[ygra]

Javadoc is tied so closely to HTML that any output format other than HTML is quite difficult to achieve.

[afandian]

It's been a while so I'm a bit rusty. But for most comments it would just be a start and end tag. You could also reference other types, XHTML style.