Myself, I would wait until 3.0 public. As of now, a lot of apps aren't compatible. If you wait until June, it'll give developers time to update their apps and make them compatible. I have 3.0 and it's a pretty amazing update to the iPhone. But in its current state, it would be best to just let it be. There's some bugs and tweaks that Apple needs to fix and make, and can hinder everyday use at times. But, if you're currently developing apps, you'll need to upgrade because of Apple's compatibility requirements.
I even bought an additional iPod to test on this my apps without having poblems with my other apps for daily useage.
