"It's my understanding that many of these planetary distances are average radii of very eccentric elliptical orbits."

Most detected planets have much more elliptical orbits than those in our solar system. Fomalhaut's newly imaged planet has an excentricity of 0.11, eccentric but not especially so.

"In fact, those planets with highly eccentric orbits probably are easier to detect when using either Doppler or astrometric methods, so they are probably overly represented in our list of exoplanets.

Not quite. A Jupiter mass planet at a 3 AU (average) elliptical orbit WOULD cause a varying doppler shift if in an eccentric orbit and the magnitude of the shift would at perihelion be slightly larger while smaller at aphelion, but since such Jovian masses are readily detectable anyway we'd have found any perfectly circular Jovians out to several AU for G and K stars. So all planets of a given mass regardless of orbital eccentricity are presently detectable out to several AU. Our solar system is looking more anomalous by the year.

First we were surprised by the Hot Jupiters which made folly of the initial planetary formation models. Now with the discovery (see chart) of superJovians at hundreds of AU from the promary the new computer models of how planets form need to be trashed. Theory had said that massive planets can't form at those distances and current migration theories didn't allow for THAT much travel. Yet again, people built computer models that in reality simply tell "Just So" stories matching the preconceptions of the researcher. There's a lesson here.

Hopefully with Kepler we'll get a major step forward in real data and have enough to build planetary formation models that maybe last a couple decades.