As expected Sun released Update 4 for Solaris 10 (also called Solaris 08/07), introducing a major enhancement in its OS virtualization technology called Solaris Containers.
New Solaris Containers for Linux Applications (codenamed lx brand or Linux Branded Zone) allows installation of CentOS 3.5-3.8 or Red Hat Enterprise Linux 3.5-3.8 distributions inside a non-global zone.
Inside these zones any 32-bit application for Linux can run unmodified, since Solaris emulates a Linux 2.4.21 kernel, glibc 2.3.2 and partially /dev and /proc interfaces.
Obviously there are limitations: a Linux Branded Zone only supports user-level Linux applications, which implies no device drivers, kernel modules, or file systems.
Sun published a list of applications known for working inside these zones.
Download new Sun Solaris 10 Update 4 here.