Sorry to be away from the discussion. Had to take a work break. I'm glad we had a few other voices in this conversation. It's an interesting topic. I knew about the Terrestrial Planet Finder, but I thought it contained only an interferometer. The coronagraph was new to me. Looks like they're hedging their bets over at NASA. Pretty slick: they packaged two completely separate missions under one name and still managed to keep it alive.
You might find these pages interesting.
NASA Terresterial Planet Finder (TPF) Technology Milestone Page http://planetquest.jpl.nasa.gov/TPF/detectionMilestone.cfm
NASA TPF Technology Plan (6.2 Mb) http://planetquest.jpl.nasa.gov/TPF/TPF-CTechPlan.pdf
TPF Homepage http://planetquest.jpl.nasa.gov/TPF/tpf_index.cfm