yes feature settings can be grouped, it is not specific to ISettingControl settings, any settings can be grouped by tabs. You should look at the feature definition file for other features like the blog to see how groups are configured.

Note that if you previously installed a feature from the UI and now you want to make a feature definition file it is very important to copy the feature guid from the ui so it is the same in the definition file otherwise you will get 2 copies of your feature when you visit the setup page.

Hope that helps,

Joe