I've had 7 vbrake 29ers..
This thread gets repeated every 4 months or so, so let me contribute my personal list. I've owned 7 29ers, all v brakes...
1-2) As others have said, any custom builder can do one with vbrakes. I have been very happy with my bilenky and I also had a generic chinese ti frame for $345 shipped.
3) Older Gary Fishers.. my mt tam from 2002 sniff sniff, RIP, I have a sneaky suspiciion that as late as 2008/9 the fisher dual sport line was basically the same frame
4) Lenz- he built me a dual susp Leviathan with Vbrake posts. Wonder if someone here still has that frame...
5) 2010 Voodo Azain- Got a killer deal, but the toe overlap in XL made me get rid of it after 2 rides.
6) 2010 Astrix Rook- LOVE IT, my current race ride.
7) Surly Karate Monkey- got the frame, haven't built it yet. Legions of fans here on MTBR.
Lots of rigid fork options, Yes white brothers will build you a custom suspension fork, but its bucks ($700+), the RST M80 fork used to have vbrake posts, you can only get it with a frame on bikeisland. I am happy to sell you my original Marzochi Marathon 29er from 2002 but its heavy and not a lot of travel.. I am bugging JB Importers to sell their little vbrake posts that come on their rigid 29er fork as a stand alone item. Stay tuned...
As for why v brakes, at least for me, in 2002 I was concerned about traveling with disc brakes to an exotic country and worrying about needing service somewhere. My original wheelset was Salsa Delgado Cross to 36 spoke 951 XTR hubs. Both the original front and rear wheels still spin pretty nice despite tons of miles and abuse. But since those were my first wheels, any other wheels needed to be v brake compatible and therefore the next frame needed to be and so on and so on.
I'm almost to the point that when my two white brothers BW 1.0s finally give out, I'll break down and get a new fork that will require disc brakes or use the JB Imports adapters, but until then V brakes rule! (Unless you happend to find yourself by accident on the NORBA downhill course at Snowshoe Mountain. In West Virginia. In the rain. On a hard tail 29er. Then not so much