The problem in jailkit has been fixed. The current CVS version of jailkit is working fine for me now and Olivier will release a fixed jailkit version soon. To get the fixed cvs release, use this command:
cvs -z3 -d:pserver:email@example.com:/sources/jailkit co jailkit
and then run ./configure && make && make install
inside the jailkit directory.
If you have a 64Bit test system, it would be great if you might be able to test it. We have also found a typo in the jk_init.ini file which is delivered by ispconfig, this is not related directly to the problem in this thread but as the CVS version of jailkit has a better config file parser, it complains about the syntax error in the old file. This has been fixed in ispconfig SVN too and I attached the fixed file as .zip to this post here too.
Description of the error and possible solutions to make the system accessible again:
There was a error in the jailkit scripts in jailkit 2.8 that copy the system librarys which only affects directorys or files that are symlinked. In Debian and Ubuntu 64 bit, the lib64 directory is a symlink to the lib directory which causes the librarys in lib to be oevrwritten or removed. A possible solution to to make a broken system accessible again is to copy the librarys in lib from a working linux system or rescue cd (must be the same version and distribution of course) to your broken system and then reboot.