Jerry is working with Dean on the new Dean Soltero. There is no "official" run of Jerry Cantrell signature models, but there was at least one run that I know about, check out these links:
Actual guitar:
http://aliceinchains.com/forums/thread/48100.aspx
Discussion/Specifications:
http://aliceinchains.com/forums/thread/35843.aspx
The thing is that I am not quite sure if there will be a signature guitar released officially. I know G&L tried to work something out with Jerry at one time and all that amounted to was the limited run of white Rampages that got out there. If you want to get a Jerry Cantrell signature I say hold out for a White G&L Rampage, a Wine Red Gibson Les Paul, or a Dean Soltero retrofitted with a Kahler.
Gear: G&L Rampage, Mesa/Boogie Mark IVA, Custom Avatar Vintage 212, G-Major, Ibanez TS-9, Morley BHII Wah