Date Reminders in Silva

Hello!

On our site we have one page where the dates for the next seminars  
are listed. So far this is done with an ordinary Silva Document  
edited with Kupu. The next date simply is added at the bottom of the  
page. In case you want to have a look it's

http://www.mpip-mainz.mpg.de/theory/seminar/group_seminar

We now would like to add some functionality to this page. 20 Minutes  
before the seminar starts there always is a reminder mail sent out to  
every member of the institute. This is done by hand by the person in  
charge of this page. This of course does not work very reliably,  
since sometimes the person in charge is on vacation and so on.

Before I start writing up something myself that automatically sends  
such a mail containing the subject and the speaker 20 minutes before  
the date I wanted to ask whether something similiar exists already.  
Also any hints as how to accomplish this quickly would be very much  
appreciated.


Thanks a lot

Timo