What steam should be anywhere near the coffee grounds?
I thought espresso machines just used it as a pressure source to force hot water past the grounds.
Or are you talking about steaming the milk?

I've read that the 'right temperature' for a French Press is something like 190F and the steep duration something like 5 minutes. Longer steeping gets you more caffeine, but also more acid. It's all a matter of personal preference and taste, though.

I'm interested to see what this thread yields...