Over the week-end, I messed up a patch to the Perl 5 Perforce repository. Apparently I've been playing too much with subversion (where there's no equivalent of the mandatory "p4 edit" command.) I like subversion.
I asked in the subversion development mailing list whether there was some p42svn conversion tool. Conversion should be easy, p4 and subversion share the principle of a global revision id. I was pointed to Barrie Slaymaker's vcp, which looks interesting, I'll have to look at this (it doesn't support subversion for now). But that's not urgent.