I make these announcements on my site 'cause folks do a lot of events (and maybe they do so many events because we've got the coordinating-times-worldwide thing sorted out and agreed upon as a community).
Other time-related suggestions you can make to your community:
* Be wary of planning events to start at midnight because people often get the date wrong (this is why ppl say "one minute past midnight")
* Try to get used to 24-hour time
* Check smoke alarm batteries at DST start/end