In Windows 7, shared folders do not have an overlay icon on them indicating they are being shared. The reason for this change is explained by Raymond Chen here:
Given the changes in how people use computers, sharing information is becoming more and more of the default state. When you set up a HomeGroup, pretty much everything is going to be shared. To remove the visual clutter, the information was moved to the Details pane. What's more, a single overlay cannot express the different ways an item can be shared, so in order to figure out what the deal is, you have to go to the Details pane anyway.
So, the best place to view your shared folders and to stop sharing them (after the sharing love is over) is the Shared Folders MMC. It can be invoked by typing
fsmgmt.msc at the Start menu.