Mervyn's is a California based division of Target Corp. Mervyn's and Target were at one point part of the Dayton-Hudson Corp (DHC), with Marshall Field's, Hudson's, and Dayton's as the Department Store Division. The DHC changed its name to Target Corp, due to the fact that Target was making the majority of the money for DHC. The Dept Store Division stores were all changed to Marshall Field's. Earlier this year, Target sold Marshall Field's to the parent company of Lord & Taylor.
Mervyn's is a store in the style of Kohl's, while Target competes with Wal-Mart and K-Mart.
I have stock in Target (TGT) through my old 401k, which I still have from when I worked there.
That's why the website changed. Used to be Target.com had tabs for Mervyns and Marshall Fields. I find it interesting how Mervyns created Target to go after the low end market and it's been so successful that it took over. I also find it funny how well they fly under the radar, while everybody focuses on WalMarts market power nobody pays attention to the fact that Target contracts their own "bonus track" version of CDs periodically (I think Bon Jovi's release last year was the first, seen a couple since then). Target is a lot quieter than Wally, but they have some serious market clout (and it's a much more pleasant store to shop in).