4x chips, 8-cores in each chip, 8 strands per each core = 256 virtual CPUs and 32x built-in HW crypto accelerators, up-to 512GB RAM, 8x PCI slots, 4x on-board GbE, 4x internal disk drives, all in 4U.
Allan Packer has posted more info on the beast.
If you consolidate applications which can easily take advantage of many threads you can get really good throughput for reasonable money - in some cases you will get better performance than 3x IBM p570 and it will cost you MUCH less.
Interesting application of the T5440 would be a 2-node cluster utilizing Solaris 8, Solaris 9 and native SOlaris 10 zones - that allows you quick and easy consolidation and migration of old environments. I did something similar in a past but utilizing T5220 servers.
T5440 PCI-E I/O Performance
T5440 Architecture Overview