"Since IBM have been bashing the UltraSPARC T1/T2/T2+ at every event I've been too its quite funny to see them make an almost exact Power-based copy."
You clearly haven't the foggiest notion about the architecture of either. The PowerProcessor is a rip-snorting, single-thread monster and sticking 8 of those on a chip is not going to change that; just the economics. No doubt it will come at the price of using a serious amount of electricity. It's vastly better suited to applications which require fast single-thread performance than is the T1/T2. For those that care, that includes things like high transactional databases where it is essential to keep code-paths short where exclusive access is required. If that's not done, then your multi-core machines will end up burning up a higher and higher proportion of their CPU waiting for spin locks.
The T1/T2 range is fine for low-power, high-throughput workloads where there are lots of largely independent threads. The T1./T2 hardware threading effectively treats the core resources as a system in its own right and despatches different parts of different hardware threads onto the core resources. A sort of multi-tasking within the core (for instance, the T1 has 4 threads per core and one integer unit whilst the T2 has 8 hardware threads and two integer processors per core). Now this is very efficient as resources that would otherwise be unused due to thread stalls for things like memory access can be used. However, it comes at the cost of seriously slower single-thread speed, especially so when the underlying core resources are over-committed (which, incidentally, means that CPU utilisation as reported by the operating system is seriously non-linear as the OS sees the hardware thread, effectively a virtual CPU, as the resource and not the core utilisation).
The T1/T2 is not a competitor to Power. Either a shop has committed itself to AIX (in which case Power is a done deal). The real competition to T1/T2 comes from the x86 side where sheer volume (and better single thread speed) is the real challenge from the latter.
The Power competes with Itanium and the SUN/Fujitsu SPARC64 IV (and the coming Rock processor), not the T1/T2. Frankly the SPARC64 IV is not in the same performance league at the moment. SUN will have to up their game on Rock, and they are going to have a hard time with selling volumes. Incidentally, Power, Itanium & SPARC64 IV all support a form of hardware multi-threading, but it's of a fundamentally different type to that of the T1/T2 which has the feature as its heart and soul. It's innovative, and clever, but it has its limitations and I think it will get steam-rollered by the x86 bandwagon.