The whole kata/bunkai discussion is (in my opinion) a crucial one to understanding of martial arts. Your statements, Bill, about forgetting whichever one bunkai you were taught, and that it is 'frozen in time' are right on in my opinion (around now is when I will stop typing "in my opinion"...). Of course, everyone is entitled to their own opinions about the kata/bunkai thing (even J.D. - yuk,yuk), but I don't think highlighting the difference between kata and bunkai is the same as saying "kata is kata and sparring is sparring." Mostly folks that say this don't appreciate the utility of kata, and mostly this is because they have not practiced bunkai.
Perhaps a definition is in order. In a martial arts context, bunkai means "interpretation." An essential component of traditional Japanese martial arts was the student "creating" bunkai for kata as a demonstration of his comprehension of the underlying principles and applications of the movements. The evolution (or perhaps "de-evolution") of this process to the current understanding of 'bunkai' - such as when an instructor says "let me see your seisan bunkai" and expects something very specific - is documented elsewhere by Mattson Sensei (recall that this was an effort to standardize the meanings of these movments to facilitate group dan tests). What has been lost, however, is the 'deeper understanding' of our kata!
Without going into the details of approaches to creating bunkai (perhaps the subject of a later post?), I think it is crucial to get away from this static interpretation of something so fluid. For those of you who cross train, take some of the movements in your 'other' style, and see where they overlap with uechi kata movments. This process can often give clues to possible meanings of movements in kata. Have someone throw a punch or a kick, grab you in different ways, etc. as you practice your kata movements. If you don't come up with lots of "duds" as you do this (you will know they are duds, as uke will still be holding onto you, or a lump will be coming up somewhere), you are not thinking creatively enough.