Yes, a lot of fixes and improvements especially from snv_122 in audio (I helped with one bug regarding this) but still support is not so good as in other OS's and sometimes you can expect "magic" things when using some headphones or audio over USB and so on.
I had in mind mainly Xsun so sorry for quite off-topic. But even implemenations of Xorg are diferen between OS as you can choose diferent approache to problem how to integrate it. The fact is that on OpenSolaris my cursor hangs every couple of seconds for second or so. In OpenBSD it works without problems and GEM is missing too. And I'm sure that OpenSolaris don't use this http://www.xenocara.org/ -- This message posted from opensolaris.org