Bolt PR goes from 10.03 to 9.69 in one year! Well, then there's hope for all 10.5 sprinters of the world --- with a similar performance "boost", you too can be world-class next year!
That would be a good improvement even for someone who had been a couch potato prior to taking up track. Sometimes kids have a late growth spurt that would improve times, but Bolt has been 6'5" for something like 7 years already.
There was an interview on the IAAF.org site last year about how Bolt was going to get "serious" about track. Now we understand. I don't mean this entirely facetiously, because I can respect that he likely has been training harder and more seriously since that time. But to train harder, there must also be recovery. Because of the way the west African body metabolizes, recovery seems to need more assistance, whether that be rest, oxygen, or drugs.
Still, a kind of congratulations is probably in order because his competitors are not exactly on a bread-and-water regimen.