Ubuntu includes a Message of the Day (MOTD) when SSHing into a system which contains some useful information about the system, but it also includes a call to motd.ubuntu.com to fetch dynamic information. Though potentially useful for sharing information about security issues and news, it has also been used for advertising purposes which is considered more of a nuisance.
It can be disabled quite simply by going to /etc/default/motd-news and changing the ENABLED parameter to:
In a commercial environment, it may be preferable to setup a website and point the URLS section to a page containing useful information. The MOTD page is simply a text file saved as HTML making it simple to advertise your own messages.
The scripts used by the MOTD can also be found in /etc/update-motd.d/ and are all well commented and easy to understand.