Another suggestion :
I found that in some specific cases like on the Stackexchange Live Podcast room, it would be useful to detect event like
"xxx happens at 11:00pm EDT" and display a tooltip to convert it to the user timezone value.
I think that some kind of conversion like this is already existing for creating events.
Maybe it would be easier to have a
Of course the first one has the advantage to not modify the poster meaning (if someone say it's 9:00pm EDT here, we don't want to change that because we know what is the current time)
It's also possible for user to go on some sites to do the conversion, but could add some value to the chat system. Maybe it has some meaning on the sites too? But I'm not sure of that. Some kind of question on gaming that would ask for a specific time on an E3 presentation? Or a developer asking for the next keynote schedule?