z4root v1.2.2
Requirements: A compatible Android Device (look below)
Overview: It is an app you install from the market or by side loading, that has a single button that will root your device.

Should be 100% safe - nothing on disk is changed besides the root binaries, so if something goes wrong, simply rebooting the device should fix up any and all issues.

V1.2.2 : Adverts added (can be permanently disabled with menu option). Hopeful fix for devices such as Moment.

Here is the list so far of known compatible and incompatible devices. I haven't actually tested these myself - I only have a Galaxy S device - but this list has been created by reports from users.

Compatible
Samsung Galaxy S (All variants)
Backflip
Sony X10
Xperia Mini
Drod 2
Galaxy Tab
Galaxy I5700
Galaxy 3 I5800
Droid X
Samsung Acclaim
Cricket Huawei Ascend
Motorola Cliq
Huawei 8120
Hero
Optimus T
Droid 1 (z4root 1.2.1)
Garmin Asus A50
Motorola Defy
LG Ally

Incompatible
Desire (requires nand unlock)
Desire HD (requires nand unlock)
Magic (unknown)
Evo (requires nand unlock)
G2 (requires nand unlock)
Archos 70 (unknown)
LG Optimus One (unknown)
myTouch 3G (unknown)
Wildfire
Droid Incredible

APK Size: 993 KB

Download:
Log in to see links