If you were at one of these events, or you will be at an upcoming event, it's easy to add yourself. That way other people searching later can see who was at an event or who is attending an upcoming event.
The first step is to make sure that you or the person you're looking for is listed on whoisi. You can search with the search box at the top of this page or you can search from the home page. If you're not listed on the site it's very easy to add someone.
Once you've added yourself there's a link to the right of your name that says "Edit". Click on that.
Then click on the link that says "Add an Alias".
As an alias add the tag listed above for your particular event. So, for example, for OSCON 2008 I would add "@oscon2008" - as in "I will be at OSCON 2008."
You can either search using the tag to see who else is going to be at the event or you can follow their stream from the event link at the top of this page.
For example, if I were searching OSCON 2008 participants I could search for @oscon2008 or I could just visit the page with the activity stream for the event. The url for the activity stream is http://whoisi.com/e/<eventtag>. As an example for oscon it would be http://whoisi.com/e/oscon2008
Enjoy!