The latest version of Mojarra 2.1.0 (JSF 2.1) contains a couple of much needed bug fixes (see http://javaserverfaces.java.net/nonav/rlnotes/2.1.0/releasenotes.html).
It also finally allows a JSF based web application to omit web.xml, something many expected to be possible with JSF 2.0 but which some wording in the JSF 2.0 spec prevented.
Although with the new excellent deployer support in JBoss AS 6 it's trivial for one to update Mojarra, it would be nice if 2.1 was bundled by default. Every change to the default configuration is one and especially if your code has to be executed by clients for which you don't control their JBoss AS installation this can be a hassle.
JSF 2.1 support will certainly be considered if/when there is a 6.1 release. But I can't make any promises. I do think it's likely to be in an AS7 release before long. Getting it into AS7 is a higher priority.