You're right you'll have to wait for Count in CMP. But to solve your problem you can use BMP. Build a BMP Bean with a getCount method that gets a connection, performs an select count(*), then returns the count. Had to do this and it works fine...at least until we get what we want from CMP.
You can use the count function in JBoss-QL as of release JBoss-3.2.2RC4 (it returns a java.lang.Long).