Let's say you want to know if some heavy weather is moving in. You have two options:
Join a chatroom? You bet! The U.S. National Weather Service uses Jabber to push out weather alerts. As Jeff McAdams explained on the new social@xmpp.org list, there's a public-facing version of this service running at muc.appriss.com on the XMPP network. All the chatrooms are of the form zz???chat, where ??? is the three-letter code for your local weather forecast office (you can find them by mousing over the map at www.weather.gov).
So let's say you live in Denver. Our local weather forecast office is "BOU" (short for Boulder, I assume, where NOAA is headquartered). Therefore you would join this chatroom:
For the Bay Area you'd join zzmtrchat@muc.appriss.com, for Chicago zzlotchat@muc.appriss.com, for New York zzokxchat@muc.appriss.com, for DC zzlwxchat@muc.appriss.com, etc. You can even talk with other weather hounds in these rooms. Fun stuff!