Girls Mode is fashion simulation in which you attempt to become the manager of a clothing store. Over 10,000 items can be selected as you coordinate clothing for your customers. If the customers like what they see, you rise in rank and are able to expand your store. The ultimate goal is to show your fashion skills off on the cat walk that's held in the town's contest area. Take top prize in these contests, and you'll find yourself with rare items.
There have been other ds games that tried the girls makeover theme, but most of those have been aimed at a much younger audience. Girls Mode seems to actually do everything right, considering it's being developed by syn Sophia (formerly Aki Corporation) in conjunction with Nintendo, so it should end up much better than most of the other girly games on the market. Some footage was shown at the start of the conference lineup video posted here. Check the 3d in that video, i must say it looks really impressive for the ds.
In Wi-Fi mode you can set up contests online where up to 4 people can take place. My guess would be that its a battle on the cat walk to see who can be the ultimate diva . In addition, items can be bought and sold through a shop online via Wi-Fi connection. Girls Mode will be available in Japan on Oct 23rd.