Are you talking about the new ejb timer implementation?
If so, would you rather see it using the jmx timer service?
Does the new Thomas Diesler implementaiton still use the Scheduler? That thing is a piece of crap. So yes, use the jms timer service if you can. Scott is also interested in integrating Quartz. Not sure if it if applicable in this situation though.
Actually, I see now that Adrian is talking about the implementation of BootstrapContext.createTimer().
As far as Thomas' ejb timer implementation is concerned, it is just using java.util.Timer.