asterisk users - Jan 2012 - RFC 5922 (TLS Certificates) and Asterisk

I've raised a bug report about this here:

https://issues.asterisk.org/jira/browse/ASTERISK-19268

I'm just wondering who else has been investigating RFC 5922 style
certificate practices?

Which CAs have been able to provide appropriate certificates?

What kind of interoperability testing has been done between the major
products (e.g. Asterisk, Kamailio, OpenSIPS, reSIProcate/repro)?