WEll mine was stuck on the scrolling circle. Had to reboot the phone and it wouldn't restore back to 4.1, Had to do the a restore in Itunes and it updated it to 4.3! I sold the phone on the premise that it was on 4.1 and jailbroken. I sent the buyer a message on ebay and am waiting for a response. Hopefully he won't be too annoyed. And hopefully a jailbreak for 4.3 will come soon enough.
Here's how to do it if you've backed up your SHSH's via cydia's make my life easier button. The guide is for windows. It's based on xp but vista and 7 are very similar.
If you pressed the make my life easier button in cydia then follow these steps to get your phone back to 4.2.1 or 4.1
How to downgrade to 4.2.1 or 4.1 on windows XP
First download the 4.2.1 firmware for the GSM iPhone 4 here
or the 4.1 firmware from here.
While thats downloading go to C:Windows/System32/drivers/etc and open the hosts file with notepad. At the bottom on a new line copy and paste this...
74.208.10.249 gs.apple.com
Once you've done that and the firmware is downloaded get your iPhone into DFU mode. Use greenpoison to guide you through it and plug your phone into iTunes. It should detect your phone in DFU and tell you to restore it. Hold shift on your keyboard while clicking on restore and show iTunes the ipsw you just downloaded. At the end you may get an error 'could not restore iphone' this is normal. Just use tiny umbrella to kick it out of recovery.
If you've clicked the make my life easier button you should be on 4.2.1 or 4.1 and able to get an untethered jailbreak with greenpoision. If not you will need to restore again normally to 4.3. You may need to delete the line you added in the hosts file to be able to do so...