Inspired by mikesee's posts, I put together some studded 29+ tires for my fat bike (Lurch w/ Bluto). I used a set of Innova Gravity Vidar 29x3.0 tires and 3/8" Kold Kutters.

Basic process:

screw in as many Kold Kutters as you feel you need per tire (I did 96 rear, 192 front, no studs in the middle or edge)
turn the tire inside out and grind down the exposed sharp points on a bench grinder
put a blob of silicone on each of the ground down points
let it dry
mount tire however you want (my tire/rim combo didn't like tubeless, so I used a tube)

No long term reports yet, but initial impressions:
ice: like velcro
hardpack: great
slush: ok
loose snow: ok, nowhere near as good as my 4.5" Snowshoes
bare dirt: good
bare rocks: annoying

I'm a bit concerned with pull-outs (none so far) and flats. If I run into flat issues, I may try a Tuffy Liner on top of the ground down points.

There is not much clearance between the Kold Kutters and the brake arch on the Bluto. No worry about actual contact, but any snow or mud that builds up gets scraped off by the arch. Avoiding the center and second to center knobs would reduce this interference. : Innova 29 x 3.0 Fat Bike Tire With Tube! Gravity Vidar Black 29 Inch Package : Sports & Outdoors

Total cost was ~$105 with lots of Kold Kutters left over...

29+ studded tires on the Lurch by Brad Baker, on Flickr

Kold Kutters by Brad Baker, on Flickr