This weekend, Activision will have a free weekend for Call of Duty: Ghosts on the Xbox 360 and Xbox One. This is, apparently, the first time such an event has taken place on the consoles. It is a fairly "common" occurrence on the PC platform however.

They are calling it a "demo" and will feature three maps (Strikezone, Warhawk, and Prison Break) across three game modes. Yes, you will still need an Xbox Live Gold subscription in order to play this demo.
For the first time in Call of Duty® history, Activision and Infinity Ward, in partnership with Xbox, will be hosting a free Call of Duty®: Ghosts multiplayer demo on Xbox Live this coming weekend. Starting Friday, March 7th at 10:00 a.m. (PST) and going through Monday, March 10th, gamers on Xbox One and Xbox 360 will be able to jump on Xbox Live and try out Call of Duty: Ghosts multiplayer at no cost. The demo will include three multiplayer maps - Strikezone, Warhawk, and Prison break; three multiplayer modes - Search & Rescue, Domination and Team Deathmatch; and the original Extinction game mode - Point of Contact. Come Friday, gamers will just need to sign-in to Xbox Live, download the Call of Duty: Ghosts multiplayer demo, and get right into a match against friends, family, and anyone else enjoying the free demo weekend.

It's weird that this is a rather limited demo and not just a full-fledged free weekend. I wonder if sales aren't as hot as Activision had anticipated, hence the need for this first-ever demo event.