We have installed a new C class blade with 64GB of RAM to try and address (excuse the pun) a memory space issue one of our users is having. It's a HP BL460 G7 with dual 6 core 2.8GHz CPUs bringing our cluster up to 188 cores. We've placed this machine in the 400M series in the interim.
Of course while we consider 64GB of RAM to be significant we're aware that other institutes have clusters with machines boasting orders of magnitude more RAM.