I wanted to see how Itanium was placing in the Top500 against one of the main competitors, IBM Power, so I drew up a little table. In terms of Gflops/Processor Itanium stacks up very well against the competition. I believe I've identified the IBM power offerings for comparison (in blue).
Rmax Sum (Gflops)
Processors
Rmax/Processor
Power4+
97098
25194
3.85
PowerPC 440
364691
169984
2.15
Power4
31092
11552
2.69
PowerPC
64377
11636
5.53
Power5
35581
6216
5.72
Power
23574
26920
0.88
All Power
616413
251502
2.45
IBM Power
187345
69882
2.68
Itanium 2
237385
50668
4.69
Pentium 4 Xeon
398724
135348
2.95
Xeon EM64T
146050
35214
4.15
Intel
782159
221230
3.54
Note there are several minor generations of Itanium's lumped together, whilst the Power line gets a bit more granularity thanks to different versions. Of course the great thing about the Top500 results is you can get a different result depending on what sort of press release you want to write today, so the whole thing should be taken with a grain of salt.