IMO, these powerbooks will be around a while yet. They just can't push the G4 much higher, and I think we're looking at summer for the G5 powerbook. So I kinda doubt that they will be updated soon... just my opinion though.
I'm in total agreement with QCassidy. However, you will want to add RAM, my 1.25GHz bogs down a bit with the outdoor levels on Halo with the standard 512MB.
You may want to consider ordering the 1.25 GHz one instead and bringing the price down by getting it with the Combodrive and a smaller 60GB HD (built to order). It won't be much more expensive than the 1 GHz model but will be considerably faster + will have an Airport Extreme card + 512 MB RAM (vs. 256 MB) + the backlit keyboard. Much better value for money IMO.