Arch Linux upgraded their gnutls to version 3.0.0. Using this new version, I'm unable to connect to a jabber server using TLS/SSL. The following can be found in mcabber.log after increasing the tracelog level:
[2011-08-20 21:51:49] LM-VERBOSE: Setting up SSL...
[2011-08-20 21:51:50] LM-VERBOSE: Could not begin SSL
[2011-08-20 21:51:50] LM-NET: *** GNUTLS handshake failed: Error in the push function.
Downgrading gnutls to a version < 3.0.0 solves the issue.