I've been a bit skeptical about predictions that the schedule change will cause performances to suffer, and I said so in the comments at Timed Finals. Scott sent me a couple of interesting and swimming-specific links in response:
Influence of time of day on all-out swimming, British Journal of Sports Medicine, C. Baxter and T. Reilly (1983):
Fourteen subjects performed maximal front crawl swim tests on separate days over 100 m. and 400 m. at 5 different times of day between 06.30 h. and 22.00 h. Performance showed a significant linear trend with time of day in close though not exact association with the circadian rhythm in oral temperature … It was concluded that maximal swimming trials are best scheduled for the evening and worst in the early morning.
Morning vs. Evening Maximal Cycle Power and Technical Swimming Ability, Journal of Strength and Conditioning, V.J. Deschodt and L.M.Arsac (2004):
… maximal power (+7%) and technical ability (+3% in stroke length, +5% in stroke rate and changes in underwater hand coordinates) were greater in the evening. The present study confirms and specifies diurnal influences on all-out performances with regard to both maximal power and technical ability.
I'll consider myself rebutted! It seems that Scott and others are right to worry that performances will be a bit off in Beijing. Of course times and world records are a big deal in swimming, because the environment can be tightly controlled and the times are a reliable indicator of the quality of a performance.
One consequence of this fact is that the FINA Olympic qualifying procedures rely heavily on time standards. Those time standards must be achieved at Continental Championships, national Olympic trials, or other international competitions approved by FINA in advance. So if you're organizing your national Olympic trials, do you try to mimic the Beijing schedule so that you test your swimmers under Olympic conditions, and give them every opportunity to get used to it? Or do you stick with evening finals, giving everybody a better shot at making the FINA time standards?
The schedule changes are given a brief mention in the latest IOC press release, but there are few details forthcoming. There's also no mention of specific changes to other sports. According to some earlier reports out of Australia rowing finals are going to be held in the evening. That's an unprecedented change, as far as I know. Will it mean faster times for the rowers? Maybe, but it probably won't have much to do with basal temperature or circadian rhythms. In rowing, like canoe-kayak, the dominant factor is the wind. Whether conditions will be better or worse in the evening remains to be seen.