Yep, cycles every three (or four?) years. The ones that expires at the end of the year are no longer sold now, so any IRCs you buy from this point on will be good up til 12-2013.

If the celeb doesn't use or exchange them before the end of the year, they're worthless.

On January 1, 2010 these IRCs won't be worth. So they have to change for stamps before that date.
In some places are selling the new IRCs and their end date is in dec 2013.

i read that the irc end date is dec 2009 so does this mean that any sent before that to a celeb will then become worthless im just asking becasue i sent to some actors in usa with irc and im sure they take like over 4 months to reply so wat will happen thanks