When I was at CERN 10 years ago, the set up was similar. Instead of Macs the desktops were PCs. The code was Fortran, Perl and c++. All work was on remote Linux boxes (typically exporting a desktop over X), although physical not virtual OS instances. You'd ssh to a gateway IP and be logged into one of the hosts. All data and user accounts were stored on a distributed filesystem AFS. There was job scheduling and management middleware that'd batch process your analysis across hundreds of hosts in the datacentre.

"The cloud" has been around for a while, although implementation has changed.