Comment 7 for bug 947236

> We'll basically get this for free the next time we merge base-files from Debian.

You will get the file for free but it will still need adjusting to have Ubuntu specific information.

As a side note, in addition to the distros I listed earlier I noticed that Gentoo also added this 3 months back:
http://sources.gentoo.org/cgi-bin/viewvc.cgi/baselayout/trunk/etc.Linux/os-release?view=log&pathrev=3203

Also Slackware have just added this to their development version, so the next Slackware version (14. 0, which is currently at RC3), will include it as well:
http://ftp.slackware.com/pub/slackware/slackware-current/source/a/aaa_base/os-release

Quantal will be the odd one out, since most of the well known distros already have this.