Just a general suggestion (not aimed at anyone in particular), ...
Try not to "sit" on relevant information - particularly if it may be or become important. One can typically send most of that information to the admin list. Since the admin list is publicly readable, one may want to strip out some details (e.g. presenter's e-mail address and phone number), but most of the rest of the stuff can generally go to the admin list. At least that way the information is there, and those of us that might send out something on the announce list or update the web site (I think there are roughly half a dozen or more, and at least a couple or more, that have the requisite access in those two respective categories) would then be aware of the relevant information and may be able to make more timely and detailed updates/announcements.
Do also try to be clear in noting status of items (e.g. possible, unconfirmed, tentative, confirmed), so one is less likely to presume incorrectly or misinterpret.
If one "sits" on the information, others may presume the one sitting on the information is going to do all or most everything relevant with that information (e.g. update web site, send out announcement, etc.). E.g., one of my rules-of-thumb is: try not to be the bottleneck in the process.