TNS, the London-based audience measurement firm that, along with TiVo, has provided the only real competition for giant Nielsen, just rejected a $1.87 billion buyout offer from WPP Group, owner of, among other things, the media and advertising agencies MindShare, Mediaedge:cia, MediaCom, Maxus, JWT, Ogilvy & Mather, and Y&R. TNS’s decision to refuse the buyout, because they viewed it as a lowball offer, quickly prompted rumors that Nielsen was preparing its own offer, which would take yet another competitive player off the market. Sound familiar?