I recently made a post on my affiliate manager blog about translating your wordpress posts for extra traffic. I have all of my pages being automatically translated with Wordpress Global Translator Plugin and I definitly suggest you try it out. I am ranking well with a lot of different foreign keywords I didn't even mean to rank for!
Does it generate readable text in the target language? Most blogs I try to translate from [non-English language] -> [English] via automated translation turn out barely comprehensible. Might be worth a try to gain broader coverage.
Obviously there will be grammatical errors, but I believe that anything is better than nothing. I've used shoemoney as an example before. Even if the grammer is bad at least it's better than nothing
I'm using it too. The translated text it's not very bad as far as I can tell but I didn't notice a dramatic traffic increase.
I have been using this at this time, after reading about it on John Chow's RSS feed, and it certainly does allow for people, who would probably not normally have been able to view your site, to then be able to see the content in a generally readable form. Your site can quickly be found from many more locations after you set this plug-in up.
It probably depends on what you're writing about. I haven't setup mine up to translate my feed yet. I might do that soon though.