A number of readers have asked me about this (admittedly opinionated) account of the session, since the account mentions the fact that I was in attendance.  I did stay for about 20-25 minutes of Plantinga's presentation, but it was sufficiently bad (in part because repetitive of arguments previously, and rather decisively, criticized), that I left and so did not see Dennett's reply.  (What Mike Almeida [UT San Antonio] says in the comments about Dennett's reply strikes me as credible, given what I know about Dennett's views.)  Plantinga's presentation, like all his writing, was certainly methodical and clear, but it seemed to go out of its way not to join obvious issues and rejoinders, and his invocation of Michael Behe's work was, in particular, quite shocking (and not redeemed by Plantinga's concession that he is not a scientist).  I did not, however, take notes and didn't even get a copy of his handout, so I can't offer any detail; so take this impressionistic recall of the event for whatever it's worth (maybe not much).  You can join a discussion of the event at the Prosblogion blog, linked above.

ADDENDUM:  Do see this comment.