XDA has rooted the Galaxy S II
I know I sing the praises of the guys over at XDA a lot but they are, in my humble opinion the best of the best in Android development right now. More evidence to support my case is that XDA forum member Chainfire has brought to us a kernel for the lucky folks who already have a Samsung Galaxy S II in their possession, and the root access to go with it. Amazingly the phone isn't even available to the masses as of yet but when ever you do get yours you can take it out of the box and root it. More amazingly Chainfire does not even have the device himself so he was able to accomplish the design of the kernel and the root exploit without the phone!
Your going to need some adb commands to get it done so cursory knowledge of adb is plus before giving this a go but don't fret I have a link to the thread that will give you step by step instructions on how to get this done. So if your interested in pushing Superuser, Busybox and the like to your Galaxy S II then head on over to the thread and grab the XKWDD kernel and the new ODIN (further details and instructions can be found at the above link) and further augment the strength of what may well be the most powerful phone on the planet. If you've got a Galaxy S II and are going to root it let me know how it goes in the comments. Later folks.