JBoss common 1.0.x, 1.2.x is the one that comes from the JBoss AS 4.x series. For jboss HEAD/5 it was broken into common-core, common-logging-spi, etc.
In general they "should" be compatible, but currently it's not guaranteed.
So we can't guarantee that an application that uses common in JBoss AS 4.x will run in JBAS 5.0 without scoping.
I should revert our dependency to be jboss commons (same as AS 4.2) so *at least* we can guarantee it will run unscoped in AS 4.2.
But this means we will have to release a different release of JBM that is guaranteed to run in JBAS 5.0 which has dependencies aligned with AS 5.0 dependencies.
Either that, or an explicit compatibility is defined and tested somehow between the old commons and the new common core etc.