The iPhone's lack of native multitasking is in my opinion its only (or one of its few) defects. Well, you can still play music while surfing the web and push notifications are probably a much better way to go when it comes to aim, nevertheless everybody would still like to see it happen.
There already are solutions to allow you to multitask thanks to the jailbreak, but the developer Aaron Ash came up with a neat new way to go around your apps, very much like on the Palm Pre.
It's already live on Rock and should hit Cydia anytime now :
