If you see something you've never seen before during an NFL game in 2010, it could be a rule change. The SB Nation Eagles blog, Bleeding Green Nation, has four posts detailing the most significant changes.
The umpire is now in the backfield. Probably the most significant change because you're likely to notice the extra zebra standing behind the quarterback. Maybe this rule would have made a difference at the end of the Green Bay Packers playoff loss to Arizona, but the change hasn't been made in response to that game. It's intended to decrease the chance of an umpire getting killed in the middle of the field.
No more hitting defenseless players. While I can see it working to protect wide receivers, it looks like another rule designed to protect the quarterback.
Tweaking the fair catch interference rule. This in response to a bizarre play last season. The Texans punt returner muffed a fair catch, but before the ball hit the ground, the Titans gunner caught the ball on the rebound. Not only did the Texans keep the ball, the Titans got a 15 yard penalty. Try figuring that one out.
The play is over when the runner loses his helmet. This seems like a good idea, especially if the NFL is serious about avoiding concussions.