Cases not involving client certificates have been demonstrated as well. Although this research has focused on the implications specifically for HTTP as the application protocol, the research is ongoing and many of these attacks are expected to generalize well to other protocols layered on TLS.
Due to the recent publishing of information regarding a TLS/SSL protocol vulnerability (previous ISC diary entry can be found here »
isc.sans.org/diary.html?storyid=7534) OpenSSL has released a new version (OpenSSL 0.9.8l). It should be noted that this update does not "fix" the vulnerability in the protocol. It appears that they have made the choice to simply remove TLS/SSL renegotiation from their package by default.