Has the parser just been changed with regards to tildes (~~~~) inside
HTML comments? It appears they used to be ignored, and are now
suddenly being replaced en masse the next time someone edits the page
(and can't be easily reverted - it just changes the sig to the
reverter's instead). See
http://en.wikipedia.org/wiki/Wikipedia:Articles_for_creation/2006-06-02-ear…
for an example.