Few good links that can help you unbrick your iPhone.

Nice facts here, 5 things you need to know about the iPhone

My 5 steps to unbrick the iPhone would be to ...
Download the 1.0.2 image from Apple's website
Use home + power button to get to the restore screen
Restore your phone's firmware image from updated version to 1.0.2
Then add a contact with the jailbreak and upload anySIM to your iPhone as shown >> here <<
Last but not least, take sometime to read the iPhone wiki which as plethora of information that will come in handy down the road.

Files that you'd require for the process can be found >> here << , arranged neatly.

Have fun hackin your phone.

Cheers :)
Kish