I have just try to test Jitsi with Felix 4.0.2 (from http://mirror.ibcp.fr/pub/apache//felix/org.apache.felix.main.distribution-4.0.2.tar.gz package) on my Linux laptop (in order to work with OpenJDK 7) and despites 613 compilation warnings (with JDK 7), it seems to compile and run fine (either with JRE 6 or JRE 7).
I wonder if we can update felix.jar soon in Jitsi. I think of Windows users which will probably download Oracle Java 7 (as it is the first Java SE choice in http://www.oracle.com/technetwork/java/javase/downloads/index.html) when they first install JRE. By the way we have seen some users on IRC and on the mailing list that had Java 7 as default JRE and reported that Jitsi cannot launch. BTW in some Linux distribution (Debian, Ubuntu, ...), OpenJDK 7 is available in repository.
I will try to test also on Windows and on Mac OS X (with the JDK 7 OS X port developer preview) this week-end to see if there are no other problems (especially on Windows).
What do you think ?