Looks like there will be at least three of us traveling from the Twin Cities metro area to the Gathering. 

Plugging my home address (on the west-side of the T.C. metro area) and MAM's address into GoogleMaps laid out three possible routes.
 
The quickest time-wise route GoogleMaps shows is heading south on I-35 into Iowa, then cutting over to the Quad Cities on the Iowa/Illinois border, then I-74 across Illinois to I-57 and into Effingham. 
 
The shortest mileage route GoogleMaps shows is taking I-94 east/south to Madison, WI, I-39 to Bloomington, IL, and then I-74/I-57 into Effingham.  Lots of opportunity for Wisconsin folks to join in along this route!
 
Just for fun we're also looking at following the Mississippi River as much as possible from the Twin Cities to the Quad Cities and then I-74/I-57 into Effingham.  Not the shortest or quickest, but probably the most fun and scenic.  (Actually this route will probably be the longest in both time and miles.)
 
Whichever route we choose for getting to Effingham we'll be leaving early on Wednesday morning (6:00AM?) with the hope of getting to Effingham in time for dinner.  Oddly enough, of the three routes GoogleMaps came up with the longest route (631 miles) is also the quickest (10 hours 25 min.) and the shortest route (604 miles) is the slowest (10 hours 36 min.).  Go figure! 
 
The return trip on Sunday will most likely be the ol' tried and true route of I-57/I-74/I-39/I-94 through Illinois and Wisconsin.  Hope to be on the road by 6:00AM to get back into the Twin Cities at a reasonable hour (I have to get up at 4:00AM on Monday to get to work).

So anyone traveling from (or through) the upper midwest is welcome to join in.  We will decide on the southbound route a few days before leaving and post that decision here.  We'll be happy to PM or e-mail our cell phone numbers to anyone who might like to join up with us.