My guess is that you might see some merchandise start to trickle out before the 22nd, but the bulk of it probably won't appear until the official kick-off. I'd wouldn't be surprised if the limited edition/special release items are hold until the official kick-off date.
Same here with the diamond ears they are reputed to be doing-I have a set of golden ones for the 50th and they were purchased in April 2005, so here's hoping!
In the Q&A portion of the Merchandise announcement on the Disney Parks Blog was a question about when the merchandise would be available. The response indicated that some things may be available shortly before the 22nd. It doesn't say which items... http://disneyparks.disney.go.com/bl...diamond-celebration-merchandise-art-revealed/
I think the 60th merchandise will start to trickle out any time now. I was there this last weekend and they debuted the first 60th pin on Saturday. A cast member at DCA told me about it and said it was only available at one location. I didn't make it over there to buy one though because I was on a tight schedule.