When does iPhone Mail check my Mail?!?!

I'm wondering this as well. On version 1.1.4 I could have iphone check for new mail automatically every 15 min., but now I can't figure out how to change this setting. My email is now only updating when I manually open the mail application. I'm using my AOL account if that makes a difference. Please help.

The setting is still there, it's just moved a little bit.
I'm working with a German user interface so I'm not sure about the English translations, but here it goes:
In the general settings there is a new item in the uppermost area. It should be something like "load new data".
Once you go in there you can activate or deactivate "immediately".
Down below you find the settings for all the applications that do not support immediate transfer – you can set it to 15 min, 30 min, hourly or manually, just like under software 1.4.
I think the Mail goes by these settings, at least it works for me.

Ahhhhhh, THANK YOU!!!!! I see what you're talking about. Now it is the third option down on the general settings, and in the English version it is labeled as "Fetch New Data". I was wondering what that was but hadn't played around with it yet. Thank you again, it worked perfectly.

So I'm guessing Email is one of the things that supports Push? Push is immediate, right?