It was announced on the main page a while back, but we don't appear to have a thread about it and there are a few guitar and gear nerds on this board. I was tempted to put this in the OB "gearhead" thread, but this is the first time a member of Pearl Jam has had their stamp put on an instrument (and I don't count Abbruzzese or Cameron's signature drum sticks) so I suppose its OK to leave this here in the main forum.

I think its kinda cool, hope its not too pricey, and wonder why Stone or Mike don't have signature models themselves. Some really terrible popular musicians have signature guitars out there. I'm sure Gibson or Fender would be interested.

Pearl Jam’s Jeff Ament Collaborates with Mike Lull to Create Signature Bass
The Jeff Ament "JAXT4" bass available in January 2012

Longtime Northwest guitar and bass builder, Mike Lull, has collaborated with Pearl Jam’s Jeff Ament to create the “JAXT4” signature Jeff Ament electric bass. This handmade instrument will be available starting in January and marks the first time any member of the 20-year-old iconic musical group has put their name on an instrument.

Capitalizing on a 25-year relationship, Lull and Ament worked together closely to create the signature model bass. The bass features a 20% oversized body, but thinner body thickness than standard Mike Lull T4 models, along with a reverse headstock. Jeff Ament personally chose all custom colors, finish, and wood configurations. The JAXT4 comes with a metal (select models only) pickguard engraved with an Ament designed T-bass logo, Jeff’s signature on the headstock along with a special Mike Lull logo designed by Jeff to be used only on his signature model. Included is a custom Ament hardshell case with a hand-stenciled logo on the exterior, along with a bag of assorted Ament custom guitar picks.
The JAXT4 will be unveiled at the National Association of Music Merchants (NAMM) Show the weekend of January 19-22, 2012 in Anaheim, California and be available for purchase thereafter.

Mike Lull Guitar Works and Jeff Ament have chosen 826 Seattle, a local non-profit, as a beneficiary for an online auction featuring two signature basses hand-painted by Ament. Details of the auction will be announced soon, with all funds benefitting 826 Seattle.

AKA: Gibson Thunderbird.

Seriously though, really nice bass.

Mike Lull is a badass.

also, is that the middle of a half pipe where they are photographing?

I think that half pipe is in their studio. They must have hung the PJ20 backdrop there.