iPhone 4 was recently jailbroken and now it is unlocked too, thanks to the Dev Team. It cannot be easier, no PC/Mac required, only the internets!
All you need are the following :

A Jailbroken iPhone 4 / 3GS,3G (it should be activated, that is a pre-req for online jailbreak)
A WiFi connection
That is pretty much it!

Step by step (best practices) :

Launch Cydia and search for ultrasn0w [if not found, then add repo : repo666.ultrasn0w.com in Cydia]
Install ultrasn0w and reboot your iPhone 4 when prompted. Turn 3G off  (Settings -> Network -> Enable …

Apple’s iPhone had little or no updates to the UI ever since its inception (2007 June). The homescreen is way too boring when compared to the ever so popular Android phones. To add some life to the existing iPhone homescreen, install a free application called ‘Element’. It is a Cydget widget. You no longer have to launch each individual app (weather, email, sms, calendar,.. updates). Following are the steps to install it on your iPod Touch / iphone.

Your iPhone should be jailbroken before proceeding.
Launch Cydia and search for ‘Element’ and …

Go ahead and follow this if you have a jailbroken iPhone 3G (Firmware below 2.2.1) and don’t want to mess around with the unlocking tools for 2.2.1 firmware.
Follow the following steps for both Windows and Mac Operating systems :
1) 2.2.1 Firmware from Apple iPhone 3G updates the baseband to 2.30 disabling the software unlock.
2) Make sure you have jailbroken your iPhone 3G Firmware below 2.2.1 using QuickPwn 2.2.
3) Now,if you have access to a Mac, feel free to download Pwnage 2.2.5 and build a custom firmware. Windows users might want …

If you are a legit iPhone customer (ATT, Rogers,…) and are looking for 2.2 firmware which preserves unlock capabilities but need a pre-activated unlike pwned and activated firmware, this is for you! Not a legit iPhone user? Follow this post instead.

iPhone1_2_2.2_5G77_Custom_Restore_ATT_1K.ipsw.001
iPhone1_2_2.2_5G77_Custom_Restore_ATT_1K.ipsw.002
iPhone1_2_2.2_5G77_Custom_Restore_ATT_1K.ipsw.003

Requirements :
Legit iPhone plan
Pwned iPhone firmware 2.1 (You may restore to this firmware only from an already pwned 2.1 firmware)
Download this program (freeware) to join this firmware file
Desire to chase the extremes of iPhone productivity!

Features :
Root Partition 1000 MB
Cydia, Installer
Not-Activated (For legit iPhone users!)
Factory default Apple logos (No pwnapple!)

Thank you iPhone Devs for such a fantastic job after a teasing wait for Pwnage 2.0.2! Pwned iPhone 2.0.1 firmware is much faster when it comes to response times and overall a stability upgrade from the buggy 2.0.
Here are the downloads to get you upto iPhone Firmware 2.0.1 (unlock for 2G iPhones, Jailbreak for 3G iPhones included). Make sure you have your SMS backed up before attempting the firmware upgrade!
Please DIGG this article and spread the message to the iPhone community worlwide!

If you want to build the Pwned 2.0.1 Firmware, …

When Cydia first surfaced in the 1.1.4 era, I thought I shouldn’t complicate the readers of iLikeMyiPhone, particularly when there is a user friendly installer.app lingering around! Come iPhone 2.0 firmware, I have no other choice but to recommend Cydia given its enhcanced performance, possibility of various critical apps (Summerboard, BossTools and the like) and an intuitive user friendly interface! If I’m selling iPhones I wouldn’t aglow the iPhone deals I have up in my shop to miss this app! Apple’s own AppStore closely resembles installer and Cydia though AppStore …