I believe Transformer Prime and Xoom have it right now. Also the $79 Ainol Novo7 tablet.
They never said they will put it off until JellyBean. The only semi-official rumor about JellyBean was that they post-poned some "major changes" that were coming to ICS initially.
I was hardly using my Touchpad before I put CM9 on it. Now it really is quite delightful to use. Really looking forward to hardware accelerated video though.
I've been running a build of CyanogenMod 9 on my Galaxy Tab 10, and I'm absolutely loving it. I really liked the tablet with honeycomb, but ICS has made it literally 10 times better and faster.
Who needs an "official" ICS? I've installed a beta ICS ROM (teamDRH) on my Viewsonic gTablet and it is as tabletized as honeycomb, though it looks better (this build has issues, but developer support is pretty impressive). The best Viewsonic could do as an update was a Froyo-based bugfix release.
Besides, people who have installed custom ROMs on their phone/tablet are likely less worried about using alpha/beta software, so I wouldn't be surprised if most of the early beta testers will be from this group.
My ASUS Slider is supposed to be getting the update quite soon along with the Transformer. Last I read a couple weeks ago it was in final checks at Google.
What tablets have official ICS on them? Is ICS even fully tabletized? I thought they had said they were putting that off until Jelly Bean.