Look at what I just installed into the rack at work:

Inside revealed:

http://idisk.mac.com/fourseason7444-Public/xserve-int.jpg

Installed but not yet powered up at the bottom of the stack:

http://idisk.mac.com/fourseason7444-Public/xserve-ext.jpg

From top to bottom:

Rose UltraMatrix KVM (x2)

Xserve RAID

Xserve G5

Xserve G5

Xserve G4

Xserve quad-core Xeon

Xserve quad(?) core Xeon. Or are they up to 8-core yet.

In the background are a stack of H-P Proliant DL380s, older ones on top, "G5" models with 2.5", 10K RPM SAS hard drives below and in between are a pair of SAS DLT tape drives. Price of those DL380s is surprisingly reasonable.