I am running gnus-stable-20100921-800-g7ad80d3 on emacs 23.2.1 on
netbsd-5/i386 and dovecot.  I just updated emacs from 23.1

In an nnimap group, typing "B m" gets me a complaint about
remove-if-not; I use this all the time to refile messages that procmail
put where I don't want.

backtrace with personal info removed:


Debugger entered--Lisp error: (void-function remove-if-not)
  remove-if-not(gnus-valid-move-group-p [0 0 0 alt\.os\.linux\.debian alt\.tv\.heroes alt\.jawade\.nl ....])
  gnus-read-move-group-name("Move" nil (3859) "nnimap+foo.example.com:")
  gnus-summary-move-article(nil)
  call-interactively(gnus-summary-move-article nil nil)