Gerry just posted some information about the new ADO.NET 3.5 Exam and the new ASP.NET 3.5 Exam, but didn't post the dates or the promo codes. I just signed up for both exams via the Prometric site and it appears both exams run from March 15th – April 4th. They are free if you use the promotion codes.
Good luck!
Update: Ok I removed the "promotion codes" at Gerry's request below. I'm guessing that Gerry thinks that someone sent me the exam information, however I simply took the promotion codes he posted on his blog for the other 3.5 beta exams which are the exam number plus "B1" and used the new exam numbers plus "B1" to get the new ones. The days are shown on the Prometric site when you register for the exam.
So I believe this is just a misunderstanding since I didn't post any non-public information, but I've removed the codes anyway. However, you can figure them out just like I did by looking at the previous codes. :)