Does Warner Bros. "rent out" their characters, or did they miss out on the changes to copyright law?

A while back, Disney lobbied heavily for changes to copyright law to prevent their characters being turned over to public domain. Therefore, you almost never see Mickey Mouse or Donald Duck anywhere unless it’s heavily associated with Disney.
The Warner Brothers characters, on the other hand, seem to be everywhere, be it Looney Toons or not. Things like Road-Runner cable, the mascots at Six flags, and a few others I can’t think of off the top of my head.
What’s the deal here? Where they too late to take advantage of the copyright changes, or is WB selling out the characters for company use? Maybe the WB was bought out and the parent company is handing out the characters to other child companies? Any cartoon buffs know the deal here?