Sooooooo badass. I picked up the parts this week: Air gun, attachments, teflon tape, and baking soda at Wal-Mart, ~$12. Ten feet of 5/8" Vinyl hose at Home Depot: ~$4.

Before:

After one or
maybe two minutes. The soda just tore the varnish right off:



I took the hose taped to the angle steel and stuffed it into an 8 lb box of baking soda. The next step is to make a hopper out of a couple buckets and a funnel.
It didn't do a whole lot to the real rust on the two subframe bolts I have pictured, but it did clean the light surface rust off of the tips:

I can't even emphasize how sweet this is - no more spending two hours going through two or three cans of carb cleaner and brass brushes, while still leaving crap in the little crevices.