There has been a way to downgrade both the iPad2 WiFi only and the iPad2 with 3G for weeks now. This downgrade is possible if you are on iOS 4.3.4 or 4.3.5. See this tutorial:
http://www.ipadforums.net/jailbreaking-hacking-tutorials-how-guides/40887-tutorial-restore-your-ipad-using-tinyumbrella-shsh-blobs.html
---BUT---
You must - repeat, MUST! - have saved your SHSH blobs for iOS 4.3.3. If you have not saved those blobs, you cannot downgrade to iOS 4.3.3.
I've removed the link to the above as these links (and downgrade/jail breaking tutorials) are readily available in this Hacking section
There are reasons why it requires a forum member to have four posts before being able to post links...
..it prevents them from posting old news containing old links from external web sites. Please read the rules about posting external links!
Marilyn