iPhone 4, despite its signal woes is a beast when it comes to processing power and pure, raw speed (a lil’ better than 3GS). Jailbreaking iPhone 4 will give you access to themes, productive tools, unlock and more. I tested this approach with a 3GS, 3G and iPhone 4. It is a multi-iPhone jailbreak and requires no computer access! It is the same as described here but I wanted to document Cydia apps for iPhone 4.
Initially, I was unsure if Cydia is even needed for iPhone 4 with multitasking, wallpaper …

UPDATE : Google Voice app for iPhone is now available on App Store!
Apple hates people bypassing the carrier’s features on the iPhone. Google’s Voice application which provides free texts and some other super cool features, all for free was never approved on the app store. Why? The carrier will be losing their share on SMS tax (20 cents for 140 bytes – really?). Smart people use unlimited texts add-on which costs $20 with AT&T.  Smarter people use Google Voice! You are paying an awful lot of money for your cellular …