Jay said:

The 10th Anniversary depends on what you consider our go-live date.

This teaser went live in June 2002:
http://www.originaltrilogy.com/" target="_blank" title="web.archive.org/web/20020624033636/http://www.originaltrilogy.com/">http://web.archive.org/web/20020624033636/http://www.originaltrilogy.com/

The original petition and forum went live on March 10, 2003:
http://www.originaltrilogy.com/" target="_blank" title="web.archive.org/web/20030329102201/http://www.originaltrilogy.com/">http://web.archive.org/web/20030329102201/http://www.originaltrilogy.com/

My forum join date is a couple weeks prior to that because I installed and tested the old software before the launch.

I'd say the 10th anniversary is tomorrow.

Oldest capture of the forum here:
http://web.archive.org/web/20030326013254/http://www.originaltrilogy.com/forum/index.cfm

Some zero-day members (join date 10 March 2003) were PSYCHO_DAYV, Bossk, motti_soL and Luke Skywalker.

There don't seem to be any of the old threads on the new software, I seem to remember there was a loss of data around 2005.