My wife has an iPod and we use the Belkin wireless FM broadcaster. In the Crossfire, when using the power adapter for the Belkin, the iPod gives some pretty good reception. In her car and my old car, the reception was sketchy at points. We live near Washington D.C., so there are a lot of stations all across the FM band which makes it hard to get an unused frequency. There must be something with the Crossfire factory stereo unit that makes it pick up the Belkin FM transmission pretty well..when the Belkin is powered by the adapter, not batteries. With batteries, there is much more static.

Give it about another year and there should be several iPod compatable car headunits. So far, Alpine is the only one with plans for an iPod specific aftermarket adapter.
One more note about the FM transmitters. They will never be anywhere near CD quality sound. Only a direct link to the iPod's dock connector will give CD quality output. To do that, you'd need a special iPod dock to RCA adapter and RCA/Aux imputs on the headunit.