Alan Coopersmith reported that he has integrated DTrace probes into X.org. This is great news; it means that OpenSolaris (and soon, Mac OS X and FreeBSD) developers can profile the X server very easily. It will likely lead to performance improvements.
DTrace is one of the best technologies to come out of Sun in a long time, and it’s one of the top features of OpenSolaris. I heard that it only took a dozen or so probes to instrument MySQL effectively, too.