I have recently been using an iPhone 3G and 3GS and I must say what a difference. The speed and responsiveness alone is worth the upgrade if you have a 3G or earlier. Or, you can wait until June when apple releases another model.
Launching Google Chrome OS Beta from a USB Flash Drive, logging in, showing web apps tab. Recorded with iPhone 3GS
Microsoft announces Silverlight is now compatible with iPhone. Will provide a QuickTime stream for iPhone to play. Where is Flash?