It's the first time this season the Ravens will do so.
Whether the Ravens wear black or white pants remains to be seen.
Along with the black jerseys, the Ravens will have pink accompanying them as well. The Ravens, along with other NFL teams, are taking part in the league's breast cancer awareness initiative by wearing pink gloves, cleats and towels (thankfully, the officials will return to yellow flags this week.)
Apparently, stats are kept when the Ravens don a certain type of attire. According to BaltimoreRavens.com, the Ravens are 10-3 when wearing their black jerseys (7-1 under John Harbaugh).
I'll go out on a limb and say the choice of clothing had no affect on the outcome of either game. But hey, they look pretty good, so that's cool I suppose.