Whose 2010 single-game performance will be remembered in years to come: Armando Galarraga's or Dallas Braden's?* I think the story that will stay in baseball history will be Galarraga's perfect game that got away, due to a bad umpiring call at first base. So, while we should feel sympathy for Galarraga, and perhaps even for umpire Jim Joyce, who blew the call, it's not quite a tragedy for young Galarraga.
This will be true especially if, as now seems likely to me, the rules will be changed--largely as a result of this incident--on use of instant replay to allow it for calls at the bases--the "bang-bang" calls at first base (of which there are many, and they are difficult, though umpire Jim Joyce's call on Galarraga's 27th out was not all that close), and the extremely difficult calls on tag plays at the other bases.
One thing they will not do is open up the can of worms of umpires' ball/strike calls at home plate to the delays and overrides caused by instant replay. And, you can mark my words, there will be a case when a perfect game will be ruined by a questionable ball/strike call (causing a walk, or preventing one).
The thing that's a little surprising about the umpiring error was its direction: I would think it more likely that an umpire would tend to err in favor of the pitcher trying to complete his perfecto, rather than taking it away. But what do I know; I'm no umpire.
*Roy Halladay's perfect game is a different case; this is a top pitcher who could pitch a shutout anytime he goes out there, and he could even duplicate his feat before his career is over. As for Mark Buehrle, the jury is still out: was his perfect game last year totally out of his character, an indication of what he could yet become, or perhaps just indicative of a very promising but inconsistent pitcher?