It's totally push between the web and iphone/touch. Either way. But you may have to refresh the web browser to see additions and deletions from the iphone. For example, if you add an event on your iphone, you may have to refresh the browser if you're already in calendar on mobileme. But if you add something to the cal on mobileme, your touch or iphone will update within 2-10 seconds.
It's the desktop syncing/push that is being debated. Number one, people feel they were misled by apple and that there was push from the mac to the web and iphone demonstrated with no manual or delayed syncing involved. Second, there is a debate over whether adding items on the web is instigating an automated sync with the desktop. It's working for some, not for others.
Thanks for clearing that up. Okay the e-mail thing worked in the end, it just took longer than calender and contacts.
As for the desktop issue, mine syncs (I change something on mobile me or the ipod touch) it gets a notification on my desktop a few minutes later or so.
I guess it will get better over time.