The new NFL overtime rule, see page 111 (introduced last season for playoff games only) finally became binding in the current playoff series two weeks ago, and then for a second time yesterday. Of most interest to economists about the rule change is its potential for teams to alter their overtime strategies in response to the element of the rule that both teams are now guaranteed a direct opportunity to score.
While it's far too early to make firm inferences about this, it's worth recounting that the primary intention of the rule was for the result of the coin toss determining which team gets to receive the kick-off (and consequently first possession) to have less power in determining the match winner (previously almost 60% of the nearly 500 overtime games since 1974). At the margin, we might also expect touchdowns to be the winning method of scoring slightly more often than previously, since it is now the only way that the team with first possession can effectively kill the game without the opposition getting the chance to equalize.
On the basis of these first two observations, it is interesting to note that the qualitative outcomes were very different - while winning the toss allowed Denver and Tim Tebow to end the contest on the first play via a touchdown, both NY Giants and San Fransisco each failed to score on their first possession, triggering reversion to sudden death as previously, which was won eventually by the former. [Disclaimer: I have only recently followed the sport, so feel free to critique this via comments.]
While this (admittedly premature) anecdotal evidence suggests that the coin toss is more influential than before, the reality is about as mixed as could have been expected. Someday - perhaps in a few decades or even within the decade should the rule be extended to the regular season, one of our esteemed TSE colleagues will no doubt crunch the numbers on this rule change when there is a sufficient (presuming due restraint exercised) sample size.