For informing speakers/presenters about presentation equipment/faclities, (e.g. video projection) etc., this covers things pretty well (particularly when also following the URLs that it also references): http://lists.balug.org/pipermail/balug-admin-balug.org/2006-August/000231.ht...
I like the wiki idea suggested earlier though, ... probably ought to create a wiki page and put the information there, ... that way it could be in one persistent place, and also get updated/tweaked as/when appropriate.