I couldn't get it. Are updates free and can be downloaded for Solaris 10? Or i must buy support to obtain updates, as in RHEL?
Security updates are free, and can be downloaded (with a free sunsolve account). All non-security updates (except those required to install security updates) are only available to those with a service contract. At least until the next solaris 10 version (u5/u6/etc) comes out, when you can live upgrade your system to get the benefits.