Anthony Franco has a nice article pointing out common objections to building Flash applications and the rebuttals one might use in answering them.
Some of which—unfortunately—I found to be unconvincing. For example, the ultimate answers to several of the issues (SEOs and accessibility) is simply to build two sites. Or “dual web experiences”, as he calls them.
Somehow I don’t see “use Flash and do twice the work” as a major selling point.