Hmm. 5.0b3 works perfectly for me on 64-bit Ubuntu 7.10 gutsy tribe 5 or whatever latest beta is, using package:
zcs-5.0.0_BETA3_1276.UBUNTU6.20070822-22320
I used this hack:
HOWTO: Ubuntu 64bit Install
Haven't tried Feisty on 32-bit. If I get some spare time, I might try and release a package that works on all versions of Debian and Ubuntu, 32 and 64bit. Clearly from the hacks I'm posting it's possible to run on all platforms with small hacks to the installer, surely a unified package makes sense.