I am on Solaris 10
cat /etc/release
Solaris 10 10/09 s10x_u8wos_08a X86
Copyright 2009 Sun Microsystems, Inc. All Rights Reserved.
Use is subject to license terms.
Assembled 16 September 2009
$ cat /etc/release
OpenSolaris Development snv_134 X86
Copyright 2010 Sun Microsystems, Inc. All Rights Reserved.
Use is subject to license terms.
Assembled 01 March 2010
$ cat /etc/release
Solaris 10 8/07 s10x_u4wos_12b X86
Copyright 2007 Sun Microsystems, Inc. All Rights Reserved.
Use is subject to license terms.
Assembled 16 August 2007
No-one said it has to be Solaris, right 
$ system_profiler SPSoftwareDataType
Software:
System Software Overview:
System Version: Mac OS X 10.6.3 (10D573)
Kernel Version: Darwin 10.3.0
and loving it 
But I've been using this one at work most of the day:
# cat /etc/release
Solaris 8 HW 7/03 s28s_hw3wos_05a SPARC
Copyright 2003 Sun Microsystems, Inc. All Rights Reserved.
Assembled 11 June 2003
OS X 10.4.11
Darwin 8.11.0
my work laptop: solaris 10 update 6
private laptop I: mac os x 10.6.3
private laptop II: ubuntu 10.04
$cat /etc/debian_version
5.0.4
At home, Gentoo Linux. At work, a mix of Linux and Windows XP.
$ uname -srp
FreeBSD 7.3-RELEASE i386
$
In my latop - ubuntu 8.10 and windows xp
Work laptop - XP Pro
Home laptop1 - Ubuntu 10.04 and Win Vista
Home laptop2 - Win 7
My Laptop: Sabayon & Windows 7. (32-bit)
My Desktop: Sabayon & Windows 7. (64-bit)
HP Server: (Practice server) I test out new machines such as Openbsd (Which I'm currently working with.)
Most of the time I'm on Mac OS X.
System Version: Mac OS X 10.6.3
But I use Fedora at work:
Fedora release 12 (Constantine)
Home: SUSE Linux 11 and Win 7
Work: Win XP Pro and almost all flavors connected with x-client.
Though, I am eager to work on MAC OS
uname -a
Linux localhost 2.6.31.13-desktop-1mnb #1 SMP Tue Apr 27 21:14:13 EDT 2010 i686 AMD Athlon(tm) 64 Processor 3200+ GNU/Linux
This is actually Mandriva 2010
uname -srp
FreeBSD 8.0-RELEASE-p2 amd64
Brand New Ubuntu 10.04
uname -a
Linux acer 2.6.32-22-generic-pae #36-Ubuntu SMP Thu Jun 3 23:14:23 UTC 2010 i686 GNU/Linux
more ./lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=10.04
DISTRIB_CODENAME=lucid
DISTRIB_DESCRIPTION="Ubuntu 10.04 LTS"