[Updated August 6 @ 10:15 AM EST]

Enterprising user rhcp0112345 over at XDA-Devs (where else?) has come up with an on-phone, one click root/unroot for the Samsung Galaxy S line of devices. It has only been tested on his Vibrant, but it should work across the line of devices.

There are no real details on the process yet - but it seems that you just install the app, hit “root” or “unroot,” and reboot your device. Sounds simple enough.

Full post:

Hey, I just wrote this up. Thanks to jcase for the information and his root for eris: http://forum.xda-developers.com/showthread.php?t=742228 This will root/unroot. No need for a PC. https://www.dropbox.com/s/pyg5sypm9qto7rw/Galaxysroot.apk If anyone can test. Thanks!

He later tested it on his own device:

Confirmed working on my vibrant. Just tested.

Nicely done, rhcp. If anyone gives this a shot, be sure to let us know how it goes in the comments below.

[Update]: jcase, who wrote the Eris root, has emailed us on behalf of himself and rhcp.

Some clown has taken it upon themselves to post the root app, or what appears to be the root app on the market. This is not an authorized distribution of our project, and the app has a different fingerprint(md5) than our's does (aka it has been altered in someway). It has the same pname, and icon. It is also credited as being my work, which that file certainly isn't. I haven't had time to take it apart and make sure its not malicious, I just wanted to give you guys a head's up in case you wanted to warn users that the market version is not from us, and may not do what it claims to. jcase

In other words, you should probably steer clear of the app that can be found in the Market.

[Source: XDA-Devs