OK, some more info:

default cyrus-imapd config has only a couple of berkeley DB files,
they're all in /var/imap.
But there's also some weird interaction between berkeley DB and the
cyrus-unique skiplist database used for other databases.

to convert the berkeley DBs:
from 4.2 to 4.3 and 4.3 to 4.4, only the log file format changed, so you
only need to run 'db4_recover -h /var/imap' with the *OLD db4 package*.

Then for the skiplist files, it looks like you need to move /var/imap/db
out of the way, recreate it (mode 0700, owner cyrus:mail).

-- 
==John Kohl <jtk@kolvir.arlington.ma.us>, <john_kohl@alum.mit.edu>
Home page: <http://home.comcast.net/~john.kohl/>