What about the just released Asus Eee Transformer? I think it meets all your criteria save 3G/4G which if you aren't part of a plan already is usually over priced for a capped service that in no way is worth while on a device designed to consume audio and video streams over the web.
I'm with the OP either some sort of realistic mobile broadband service or leave it out. Heck even the ability to swap out SIM cards as needed would be good.
Also while not the best of devices there is that one Viewsonic that whatever was running on sale last week. Not perfect but a heck of a lot less expensive than the other more refined devices like the Xoom or GT (really like both btw but just don't want an Android device...)
Me? I am waiting for better windows devices if they eeeever come about.
Also check out the tablet portal on Amazon. It has most of the mainstream as well as some detour devices so you can compare pretty easily.
http://www.amazon.com/b/ref=amb_link...pf_rd_i=565108