[cpeterso]

No. Firefox's multi-process support ("Electrolysis" aka e10s) is only enabled in the Nightly channel. Firefox does not yet use tab-per-process like Chrome. Nightly only uses two processes: one from the browser (the "chrome" process) and one for all tabs (the content process). You don't get crash or security isolation between tabs when they all share one content process, but that process can be sandboxed by the OS and it reduces memory overhead. Firefox will later experiment with multiple content processes, comparing one vs N tabs per process.

[kuschku]

It already does. Electrolysis allows you to specify how many processes you want to allow maximum.