How to discover what Linux distro is in use

cat /etc/*release

$ lsb_release --all
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 8.04.1
Release:        8.04
Codename:       hardy
$ lsb_release -i
Distributor ID: Ubuntu

$ uname -a
Linux blue-laptop 2.6.24-21-generic #1 SMP Tue Oct 21 23:43:45 UTC 2008 i686 GNU/Linux

[anton@localhost ~]$ uname -a
Linux localhost 2.6.26-ARCH #1 SMP PREEMPT Tue Aug 26 21:15:43 UTC 2008 i686 AMD Athlon(tm) 64 Processor 3000+ AuthenticAMD GNU/Linux

uname -r

setenv DISTRO ` cat /proc/version | sed 's/.*(//' | sed 's/)).*//' `

export DISTRO=` cat /proc/version | sed 's/.*(//' | sed 's/)).*//' `