After years of no universal ranking system, the UFC will be introducing their own cumulative ranking system, voted on by members of the media. The rankings, which will be compiled by FightMetric after every live UFC show, will be posted on UFC.com 24 hours after each event. The rankings will also be used on UFC broadcasts to better explain where a fighter stands in the pecking order of each weight class.
Pretty much every MMA website puts together rankings for each weight class, so it's appropriate for the UFC to finally accumulate all of them together and flaunt them on their broadcasts. When the UFC began using FightMetric's stats during fights (takedowns, strikes, etc), it was hailed as a step in the right direction towards legitimizing the sport in the eyes of many. Now with official rankings, the UFC will be taking another step towards legitimacy.
I can definitely see a problem with this, though, and it has to do with title shots. For example, welterweight champion Georges St Pierre will be defending his title in March against Nick Diaz. Diaz isn't ranked in the top ten by MMAFighting or MMAWeekly and is ranked fourth by Sherdog, Johny Hendricks is ranked higher than him on all three sites, as is Carlos Condit (who St Pierre beat in his last fight). Yet, the lower-ranked Diaz (who hasn't fought in a year, and lost his last fight to Condit) is getting the title shot. At least in the light heavyweight division, where Jon Jones will be defending against Chael Sonnen in March, Jones has beaten the #3 and #4 ranked fighters (according to Sherdog), and was supposed to fight the #2 ranked fighter (Dan Henderson) before a knee injury led to that fight (and entire PPV, for that matter) getting canceled.
The universal rankings are definitely a good move for the UFC, and if they make all of the ballots public (like many are clamoring for college football to do all season long), this could be an even bigger step in the right direction for the long-term legitimacy of the company.