Apple’s MobileMe – the successor of .Mac, silently changed description of their offered services. You remember the advertisement “Exchange for the Rest of us”? Now Apple decided to remove the notion “Push-Service” of MobileMe and replaced it with the notion “Synchronization”.
Instead of being pushed instantly, data will now be synchronized every 15 minutes. That simply is not a push-service. Update: an instant sync will still be possible when using an iPhone or an iPod Touch. The price will remain the same (at least) in Europe: 80€/year.