It's not easy to made up your mind on this kind of things.
For the same website I've got 3 domains: .fr .com .co.uk. To start with it was to avoid peeps to buy the same name.
I used have my content in French only and redirected all the traffic to the .com using 301.
Now I've got all my content translated from french wonder what would be the best thing to do: www.domain.fr : french content www.domain.com : english content
or keep the 301 and go for
www.domain.com/fr/ french content www.domain.com/en/ english content
The obvious seems to use .fr for french and .com for en but what's about the co.uk? I'm planning on get it translate in Spanish and German, using
/fr/ /en/ /es/ /de/
It will be easier and cheaper than buying more domains.
I'm planning to do my change in 2 weeks and once it's done, unless I start to create long and painful rewrite rules, I will loose my google rank...
Please share all your ideas and point of view.