I use a swap partition on everything although on my workstations they are rarely if ever used. In server environments, though, especially for virtualization servers, I always use some swap. In those cases I calculate my total available virtual machines using a formula like this:
# of VMs = ((RAM+swap)/avg memory per VM)
I don't think, given the relative cheapness of RAM and harddrive space, that there's any concrete justification to configuring swap as 2 or 3 times your system RAM - not on a workstation or laptop, anyway. But in a server implementation I can see that swap is going to be used.