Very experimental Lenny and SID Cyrus-imapd-2.4 packages are available from ChezOuam repository.
There is activity about this on Debian Cyrus Team development mailist this month.
As explain, official Debian packages comming soon !
I hope that Debian official real activity will continu, and Cyrus 2.4 be available – at least – in experimental soon (dream about Squeeze1…). If so, my own packages are already deprecated ! If I can help, I will help official team.
Packages from ChezOuam repository are my own work based on Debian Cyrus 2.3 develoment subversion. They don’t have public revison control system and only binaries packages (AMD64) are available for now…
I don’t do any test about migrating from previous Debian official Cyrus packages, I don’t think that this works fine.
Remember that ChezOuam packages are unofficials and must be consider as very experimental.