I just got back from buying stamps for myself. I had to go to four different Post Office branches to get them, though! They "weren't in yet."
I went to one yesterday (since usps.com said the stamps were supposed to be released on the 28th) but was told they had the stamps but couldn't sell them here until the 29th--I got the impression the 28th release was only in one place, while everywhere else had to wait until today. I went back to that branch this morning, but still couldn't buy the stamps--they were in the safe, and the manager hadn't come in yet, so they couldn't open the safe. Sheesh.
Anyway, I have some now, and I was told this is the first time the Postal Service has issued a sheet with eleven stamps on it instead of ten (that's ten muppets and one stamp of Jim). They're only sold in sheets, I was told--you can't buy just one stamp.
You can also buy a Muppet "Staying in Touch Kit" (or something like that) that includes the stamps as well as note cards featuring Muppet photos (the same photos as the stamps, I think, but I might be wrong) and envelopes. I wasn't interested, and I don't remember the price on that.
I wish they'd used better Muppet models instead of the infamous "poser" Muppets, but otherwise I'm pleased.