I always wanted to try my hands on to Open Solaris since the day Sun announced that it is making its Solaris operating system open source. I had worked with Soalris 2.6 (read Solaris 6) and Solaris 2.8 (read Solaris 8) as a server operating systems and have found them to be quite stable and rock solid.
Trying out Solaris 10
I downloaded Solaris 10 from Sun’s website to try installing it on my Dell OptiPlex PC (PIII, 256MB), but backed off after finding that it is too slow and took very-very long time to go from one step to another. While thinking about it I realized that Solaris kernel has been designed to work for a server (typically with multiple processors) like a server and hence there are lots of things which this kernel is doing which are not required in case of a PC Server. So I dropped the idea of trying out Solaris 10 for now. I have an old Compaq (now HP) ML370 lying in my server room and might give it a try on that box someday.
OpenSolaris
Next in my quest for learning 
I downloaded the four CDs 
of Soalris Express Community Edition 27 and as I was installing it I realised that this is exactly Soalris 10 (with minor differences, ofcourse) and at some point during the installation I found that this is actually internally being treated as Solaris 11 (SunOS 5.11) by Sun. Overall I found that although still under development OpenSolaris to be quite impressive and with a bright future.
GNU/Solaris
GNU fans (like me) will be glad to know that there is a product called Nexenta GNU/Solaris which is based on OpenSolaris. I downloaded the CD last night, burnt it and installed it. Debian users will feel like home. It is a Debian GNU system with a Solaris kernel. It is not an official Debian project yet.
Bottomline
Solaris is a very powerfull kernel and combinig GNU tools and Solaris will definitely give GNU/Linux a tough competition.