If this is your cup of tea, do it. It's a first-class event organized by first-class folks, the roads and surrounding scenery are gorgeous, and it's absolutely, 100% FREE. If you're inclined toward extending the adventure, you can start with me in the wee hours the day before Almanzo, riding from HC to Spring Valley, then riding back on the third day.
Of course, you'll likely need a new bike for this, even if you already have nine bikes ready to roll. It just so happens that almost every bike we sell at Hiawatha Cyclery is gravel-road capable, if not excellent. For example, a Rivendell Sam Hillborne is either a road bike, a touring bike, or a rough-stuff monster-cross bike, depending on which tires you put on it:
These are $1000-1250 for a frameset, or $1900-2500ish for a whole bike.
Or how about a Surly Long Haul Trucker? If you are a one-bike or a two-bike person, this should be the one (or two). Get one that takes 26" wheels for the added tire clearance. Here's one rigged for hauling panniers, but it could easily be set up to be (relatively) light and fast, or with knobby MTB rubber, or...
The new 2011 price on these is $1200, but if you order and pre-pay for one in the month of January, we'll honor the old price of $1095 and include some freebies.
We also have some previous year Redline 29ers that are marked down to insane-o low-ball prices: $600 for either a 17" Mono-Cog Flight or a 19" D600 (steel is real). I love how these ride, and recently configured one for my own back-road adventures.