whatching all these reporters at the daily NASA briefing asking again and again if the "tile damage" will cause any problem, and if the chine perturbances* might blow the shuttle to pieces, leaves me amazed. it's not that suddently everything goes wrong. my guess is that these kind of minor damages happened before, and were not a problem, and won't be a problem now either.
i know this is the kind of line of thought that eventually brought the Columbia down, but from what i see, the only reason reporters are asking about this is because now is the first time we can actually see them in orbit. in the past, we only saw the remains of the chimes after landing, and the flight computer managed to get over the disturbances.
* these chines or whatever they are spelled are small and thin pieces that are inserted in the gaps between the tiles on the shuttle. sometimes, some of them fall off, or partly fall off, and stick out. and when you travel at Mach 20, it starts to become a problem.