However, it seems there is a solution for those who simply need to have some video connection over 3G right now. It's called My3G and is a $3.99 app that's for sale at the RockYourPhone app store. In order to get it though your iPhone 4 needs to be jailbroken.
What My3G does is to convince your phone that it is using Wi-Fi, while it is actually using 3G. So simple, yet so brilliant. Another cool use it may have is to let you watch high-quality YouTube videos over 3G, for example. To top it off, the app features some nice setting that allow you to choose whether or not a certain application should be using it.
You can get the My3G app here.