The file /etc/issue is intended to describe the system to the user at the login prompt (when not using these new-fangled X terminals).

It can be altered by the sysadmin, but generally isn't.

On Ubuntu Dapper it contains (by default):

Ubuntu 6.06.1 LTS \n \l
[download]

and I'd expect it to be populated on all/most other distros. Might be of use.

And out of interest...why do you want this info? ;-)