Direct quote from the report from digitimes:
"In terms of individual processors, there are now 142,065 Xeon CPUs, 42,048 Itanium 2 CPUs and 10,572 other CPUs from Intel in use in TOP500 systems. Apart from the massive growth in adoption of Intel CPUs, IBM's Power CPUs have more than held their own through several generation migrations. The latest IBM Power5 dual-core CPU, with simultaneous multithreading, was featured for the first time in this issue of the list, with 720 processors in a single system. Just eight systems helped boost the number of PowerPC CPUs based on IBM's Power4 architecture to an amazing 51,664 CPUs. AMD's initial spurt to 22,230 CPUs in 34 systems in June, from 7,142 CPUs in 13 systems reported in the November 2003 list, seems to have stuttered, with 25,296 CPUs used in 31 systems in the latest issue. HP has been dropping its ranking in terms of total number of systems in the top 500, while increasing its number of CPUs."
There is also a chart/graph in the article which discloses all the big players who have sort of dissapeared in the years since Itanium/Xeon started on the list.