"Solaris 10 provides a number of new facilities over earlier
versions, including Dynamic Tracing (DTrace), Solaris Containers
and a brand new way of managing services that were traditionally
controlled through the /etc/init.d and associated directories. To
help prevent downtime, Solaris 10 also incorporates predictive
self-healing, which becomes particularly useful on Sun hardware as
it can identify underlying issues and even automatically disable
components to prevent more problems occuring.
"Solaris 10 is free, with no end-user restrictions, if all you
want is a binary distribution of the Solaris operating system. More
significantly though, from the perspective of the Free/Open Source
Software (FOSS) community, is that Solaris 10 is also available in
a open source version called OpenSolaris..."