Yep but it's pretty much been like this.
February 17, 2009 (North America); February 20, 2009 (Europe): Brawler Pack including alternate costumes for: Zangief, E. Honda, Rufus, El Fuerte, and Abel.
February 24, 2009 (North America); February 27, 2009 (Europe): Femme Fatale Pack including alternate costumes for: Chun-Li, Cammy, Sakura, Rose, and C.Viper.
March 3, 2009 (North America); March 6, 2009 (Europe): Shoryuken Pack including alternate costumes for: Ryu, Ken, Akuma, Gouken, and Dan.
March 10, 2009 (North America); March 13, 2009 (Europe): Shadaloo Pack including alternate costumes for: Seth, M. Bison, Sagat, Balrog, and Vega.
March 17, 2009 (North America); March 20, 2009 (Europe): Classic Pack including alternate costumes for: Guile, Dhalsim, Fei-Long, Blanka, and Gen.
That's just base SF4 though.