Opera has just announced that their Opera Mini browser for iPhone has been approved [Free - iTunes link]. According to Engadget, it's already popping up in some international App Stores and should/could be in your App Store any time now. Update: looks like it's live now, go get it!
This also means it doesn't use as much data, and can thus usually display web pages faster and with slower data connections than a full-on browser -- especially useful for people on roaming data rates or on EDGE connections.
It breaks SSL encryption by necessity however (https sites), so while you may want to use it to traveling the outskirts, you'll like want to avoid it when mobile banking downtown.
(You also might want to use it for it's on-page text search feature -- something even iPhone OS 4 still lacks.)
Let us know when Opera Mini appears in the App Store for you, and if you try it, what you think of it. Video of Dieter checking out the pre-release version after the break!
[Thanks to everyone who sent this in!]