Rumors are flying about the intarwebs right now about the Xbox 360 version of Call of Duty 4 possibly getting an online co-op mode via a premium content download.

Speaking at the Activate Asia Pacific conference, Infinity Ward’s Grant Collier was asked if a co-op mode would be added to the game. His response:

“Uh, no, I’m not really supposed to say anything about that… but I’m a big fan of Xbox Live and downloadable content.”

When directly asked whether an online co-op would be made available as Downloadable Content through Xbox Live, Collier grinned nervously, practically beaming as he said nothing more.

No word has been spoken on other versions of the game, but I doubt Activision would develop a co-op mode and restrict it to the Xbox 360 only. Co-op is all the rage these days, so I’d venture to say this rumor is true and we’ll see co-op coming to all versions of Call of Duty 4.

Infinity Ward just sent over an email letting us know that the Call of Duty 4 beta on the Xbox 360 will get an update Friday morning at 10am PDT (1pm EST). The update will increase the Rank cap to Level 16.

This is going to allow you to rank up and unlock more weapons, more perks, and more features; including Clan Tags (lv. 12). This is the first of several level increases we’re going to do throughout the beta, so keep playing, and we’ll keep you informed of incoming updates.

If you’re maxed at Level 11 right now, get ready to keep moving up tomorrow.

Hit the jump for more…