Same problem for me. This just started this past week. I'm still running 2.0.1. It's bugging me. This is the only thing so far that i have little patience for. 2.1 can't come soon enough i hope this email glitch is fixed.
I am getting the same problem, some days it works fine other days no email until I go to the account and it then fetches and downloads emails. Thought it may be a Yahoo issue but I am beginning to think it is the iPhone not receiving the mail. Having had a Blackberry previously, this is the one feature of the iPhone which is very disappointing.
Anyone have a idea why the Push email stops working after being idle for a bit? I receive new emails on my work pc, but then my iphone stops until I wake it up basically?
I am using Wifi at work, and home since it is available.
I restored my first generation iPhone as a new phone last night, with all the attendant headaches. This morning it stopped fetching email. Save yourself the trouble; as reported above in this thread, this turns out not to be a permanent solution.