Hello again,
I have just upgraded to a 3G iPhone from the original and I rapidly found that nothing would push to my phone.
The fix that now has my phone working reliably is to go to Settings>Fetch New Data>Push>Off. Then turn the phone off.
Now turn the phone on, and go to Settings>Fetch New Data>Push>On. Then turn the phone off, and then on again.
Please let me know if this helps.