Like Paul H. I've been looking skeptically at that Macintouch fragmentation report. Certain enlightening messages posted there suggest to me that the fragmentation issue is a bogeyman, born of old-school Mac expertise applied uncritically to OS X. Look through the report for definitive descriptions of performance problems resulting from fragmentation. I couldn't find any.

There are definitely some unanswered questions, but IMO the moral at this point is: Let OS X be OS X. (I wouldn't mind seeing Macintouch, which I think is an excellent and highly professional site, display more Unix savvy in their OS X reports.)