Solaris OS Patch Management

Please read the below notes to understand the different Solaris releases
( Marketing / Update / Maintenance ) :
http://www.oracle.com/technetwork/systems/patches/solaris/index.html
http://www.oracle.com/technetwork/systems/articles/patch-faq-jsp-139997.html
https://blogs.oracle.com/patch/entry/solaris_patches

To list all patches applied on a system , run
% showrev -p
% patchadd -p

To look for a specific patch , run
% showrev -p | grep 113964

uname prints the basic information about the system
% uname -a
SunOS dnagac08-3 5.10 Generic_138888-03 sun4v sparc SUNW,T5240

% cat /var/sadm/softinfo/INST_RELEASE
OS=Solaris
VERSION=10
REV=0

If you need to look-up a patch , you can do at support.oracle.com . The below blog should be helpful :
https://blogs.oracle.com/patch/entry/searching_for_oracle_sun_patches

For removing a specific patch , the patchrm command can be used passing the patch id.

To check for the Operating Environment / System updates , run
%cat /etc/release
Solaris 10 10/08 s10s_u6wos_07b SPARC
Copyright 2008 Sun Microsystems, Inc. All Rights Reserved.
Use is subject to license terms.
Assembled 27 October 2008 <== This also can be looked-up

The first line summarizes the release details ( broken up below ) :
Solaris 10 : Base OS Level
10/08 : Release Date
s10s_u6wos_07b : Solaris 10 sparc update 6 ...
SPARC : Hardware

SunoS --> Solaris
5.3 --> 2.3
5.4 --> 2.4
5.5 --> 2.5
5.5.1 --> 2.5.1
5.6 --> 2.6
5.7 --> 7
5.8 --> 8
5.9 --> 9
5.10 --> 10