County-level population numbers from the 2010 Census came out a couple days ago, and I've been trying to draw a map aimed at getting the population of each district as close to the ideal of 761,589 as possible while still retaining some degree of compactness. (Obviously, more compact districts could be drawn if one is willing to have a greater degree of variance in population.)  Here's the best I've done so far:

I drew this map by starting each district in a corner of the state and swapping around counties until the populations were roughly even. The largest district (IA-2) is 100.03% of the smallest district (IA-1) in population.

District 1 (Blue)
Population: 761,512
2008 Presidential Vote: Obama 57.5%, McCain 41.3%
Incumbents: Braley (D), Latham (R)

The First District stretches all the way from Ames to Davenport, taking in Dubuque and Waterloo on the way. It includes both Braley and Latham's homes, which is an incumbent-vs-incumbent matchup I haven't heard much talk about.

District 2 (Green)
Population: 761,748
2008 Presidential Vote: Obama 57.7%, McCain 41.0%
Incumbent: Loebsack (D)

The Second District keeps Cedar Rapids and Iowa City together, and then sweeps south to include Burlington, Ottumwa, and most of the southernmost row of Iowa counties. It's pretty clearly an updated version of Loebsack's district, and is the most Democratic in the state.

District 3 (Purple)
Population: 761,555
2008 Presidential Vote: Obama 53.4%, McCain 45.3%
Incumbent: Boswell (D)

The Third District is based in Des Moines, but reaches north to take in Fort Dodge and includes a number of rural counties to the south. The obvious incumbent is Boswell, although the PVI of EVEN will encourage a strong Republican challenger.

District 4 (Red)
Population: 761,540
2008 Presidential Vote: Obama 47.9%, McCain 51.0%
Incumbent: King (R)

Easily the most Republican district in the state, the Fourth District includes most of northern and western Iowa, from Council Bluffs to Sioux City to Mason City. I'd expect King to hold this seat.