20 hours standby. That has got to be the longest battery life I’ve eked out of my jailbroken iPhone 4. As you probably know—and don’t believe anyone who says otherwise—jailbreaking does impact battery life. I’d be happy if I made it through a work day— typically 8 hours of usage, 14 hours of standby—without my phone dying on me.

The small feat you see above is made possible with Auto3G [US$5.99, available from the Cydia store], an app that automatically turns off 3G connectivity for 2G (GPRS, or Edge, for you guys in the States) whenever you sleep/lock your iPhone. 2G connectivity requires much lesser power draw than 3G, but at the expense of speed, which is what I imagine you’d want while using your phone; Auto3G essentially gives you the best of both worlds at the touch of a button. You can whitelist apps that you’d like to always have 3G connectivity—apps such as Flickr and Skype, for example.

Released a couple of weeks after Auto3G, iControl [US$4.99, available from the Cydia store] does one up with the ability to toggle Wi-Fi and Bluetooth, along with everything else Auto3G can do. In addition to Auto3G’s whitelist feature, iControl lets you blacklist certain apps that it’ll automatically kill when you sleep/lock your phone.

I’ve only begun using iControl for a day, so, while this is not quite an endorsement yet, iControl offers a finer degree of control and is well-polished enough for a 1.0 release for me to recommend it over Auto3G.

Oh, if the developer of iControl is reading this, I have three suggestions for you: 1) Get a product webpage up; 2) Please change the app icon; a hand squeezing a battery, rendered in comic style? C’mon, you can do better than that; 3) And don’t get me started on iControl’s status bar icon, which I mistook for a green banana the first time I saw it…