Here is a simplified step by step that I hope helps you out.
1. Make sure and sync your iPhone to your computer ahead of time. Check Windows contacts just to make sure there is an entry for some contacts you know you have added recently.
2. Upgrade to 2.0 using iTunes.
3. Follow the link here
http://www.modmyi.com/forums/news/25...-released.html to Pwn your Iphone.
4. Set it up as a new iPhone in iTunes once everything is done.
5. Once everything is done, click on your iPhone in iTunes. Click on the info tab. Check the "Sync Contacts" box. Scroll down to the bottom and check "Overwrite info on this iPhone" box.
6. Voila. you have your contacts just as they were before.
Now don't take my wording to heart as everything is not worded exactly as you may see it but those steps are simplified and pretty self-explanatory if you semi know what you are doing. I hope this helps. Reply if you have any doubts/questions.