To an extent, it's unfair comparing Solaris with desktop Linux distributions. If you compare
Solaris to RHEL or SLES, it doesn't fare as badly. For instance, desktop Linux distributions
have power management functionality that's still nowhere near present in any shipping versions
of Solaris. Enterprise Linux distributions aren't likely to ship that functionality until next
year, and they're the market that Solaris is competing with.
(Though, really, I expect we'll still be ahead on power management for a long time. Solaris
isn't anywhere near supporting a tickless kernel and that's one of the major factors in the
idle power consumption on modern hardware)