Thanks to intrepid iPhone problem-solver and electrical engineer Renaud, tethered jailbreaking may become a thing of the past. The iDongle holds a standard 9-volt (PP3) battery and has its own dock connector to link up to an iPhone 3GS running firmware 3.1, 3.1.1 or 3.1.2.
This "standalone tethered boot" allows the iPhone user to reboot their jailbroken device anywhere, anytime, without a computer. In addition, the iDongle will even jailbreak and/or hacktivate your iPhone if necessary.
iDongle has its own mini-USB port for software upgrades when future jailbreak solutions are released (3.1.3 could be next). The tool does not unlock your iPhone, for that Renaud recommends Geohot's "sn0w" or the Dev-Team's "ultrasn0w" packages, both available on Cydia after jailbreaking.
Right now there are only a handful of fully operational iDongle units in existence as they are all hand-made from custom parts. Renaud is taking orders and donations to bring his concept to mass production at an estimated cost of $40 USD each.
The iDongle can even be used to connect your iPhone to the computer for syncing using a standard mini-USB cable. Hopefully the next round of prototypes will have an exterior case as well designed as the insides.