Massive Translation for site

I just had a question regarding translations and kind of a how to procedure behind doing them. The scenario is;

A corporate website that has over 600 pages. If we where looking at doing translations say into French and Spanish, what would be the methodology behind doing this? If the translations where for specific pages. I look at other large dynamic sites and I have no idea how they do their translations so quickly.

The procedure I imagine is;

Written Content -> Inserted into page -> Sent to Translator ->Content Sent back -> Translated content inserted into 'switch'.

that about right? I would think it could take a few days to do some minor updates and such. Any feedback?

Cheers