Darren Rovell of CNBC's Sports Biz is reporting that from April 1 to August 28, the leading jerseys in terms of sales at NFLShop.com include Brett Favre's Vikings gear at #1 and Michael Vick's Eagles debut at #4. Considering how late in this fiscal period both guys signed with their new teams, that's saying something. Vick is the only Eagle to crack the top 20.
Well-known players changing teams usually leads to a spike in jersey sales, but I say "well-known" here because it fits better than "popular" when it comes to Favre and Vick, who are probably the two most polarizing players in the NFL right now. I still have yet to see someone wearing a Vick jersey in person, but I'm sure that will change any minute now.
By the way, if you're on twitter, I highly recommend following Rovell @darrenrovell1.