I apparantly am not allowed to use trac for this (nor can I find a way to log in with my wp.org account), so I figure that I report a bug here :) .
As a matter of purism, I serve my blog as
xhtml+xml for browsers that support it. However, quite a lot of these are picky when it comes to named character entities. I got rid of them in my theme and
wptexturize already is taylored towards this issue as it seems to produce solely numerical entities. However, I got a complaint the other day from a Safari user who got an xml error because of the presence of
&raquo; on my blog. Looking for the source, I found out that
template-functions-general has two occurences of
&raquo; which imho could easily be replaced by their numerical counterparts to ensure that blog owners can easily use xhtml+xml plugins without any hassle if they wish to. There may be similar entities in WP's code that I didn't find yet, but I hope this gets fixed in the next release :) .
Note: I fixed it myself, so the given link won't show the anomaly.