I had the Club Nintendo announcement page bookmarked, and when I went to check it this evening, I found this!
I immediately checked out the rewards section... sure enough, we're getting the Game and Watch DS collection, for 800 coins. There are also some cool Mario and Animal Crossing DS cases, which hold 9 cards and 7 stylui for 600 coins, as well as some playing cards and Wii Remote holders. Wii games are worth 50 coins, DS games 30 and Wii Channels and VC/WiiWare will be worth 10 or 20. You can also compete in surveys after the game release for 10 bonus coins. You gain gold status after you earn 300 coins and platinum after 600.
I immediately began to transfer over my MyNintendo account, and in my haste, pressed the "Print Screen" button on my keyboard... which is fortunate for what is to come later.
I entered all my info, and it asked for some additional info and then said my account transfer was complete... but then I couldn't login. I tried to transfer again, and it acted the same, as if I hadn't transfered at all. After the second time, I gave up, figuring maybe I had to wait for a confirmation email, and then... browsing to another page I got the 404. The site had reverted back to it's former "announcement" status.
Anyway... I hope some of this info is useful to you! I just hope I didn't bork my account trying to transfer over too early...