With a lot of non-Intel Macs kicking around, and with people already talking about buying another cluster of the new Intel iMacs, computing at Exeter is going to be in transition for the next couple of years.
I've gone through several of these over the years, including the shift from VAX/VMS to a mix of DEC Alpha and Sun workstations, and then from those to clusters of Linux beige boxes, and most recently from Linux to Macs clusters. However Apple's move to Intel architectures won't really effect us as much as it might have, as we still have Linux boxes around and were therefore already operating in a mixed environment.
However since I'm at least partially responsible for the system administration of our current Mac cluster, and will probably be responsbile for any new Macs, I'm going to be following the PPC to Intel transition very closely.
The good news is that it looks like the essential admin tools are going to be able to cope with mixed architectures environments out of the box. More good news is that target-disk mode should still work with the new Intel based Macs. The best news is that at least some of this goodness should be available already in the 10.4.4 update. You can't complain really...
Update: ...well, not much. Rui Carmo has taken a look at 10.4.4 and it seems that the Bluetooth Updater may have some problems.
Update: It also looks like we have some incompatibilities between the partition tables on Intel and non-Intel Macs. Nothing is ever easy, is it?
Update: ...and Rui is still having problems with 10.4.4.