edit: having tested a bit - it seems gprs push works perfectly. when I send an email to myself from another account, the email is pushed to my iphone and appears with a notification without me having to do anything. choice!
however, I'd like this functionality with Wifi as well - as I'm much more likely to be connected to Wifi than anything else (home/work/hotspots) however, if this is how it works I shall suffer in relative silence until. but if anyone knows a way to get it to notify properly in wifi mode please update :)