Facebook announced Groups feature yesterday, which would allow you to create and communicate with a small set of people. However, as of today, I am finding groups a bit of nuisance because of the number of notifications I have been receiving for it.
The problem is that, anyone can add you to a group, so whenever that happens you receive a notification. To top that you receive notifications whenever someone adds a post to that group.
In order to stop group notifications, first of all go ahead and click on the "Unsubscribe" link available in the group. Secondly, on top of the Groups page, you will find an button to "Edit Notifications".
Click on that button and select the radio button next to "Never notify me". In addition to that you may also want to disable Email notifications to your account.
To completely disable Group notifications, go to edit your account notifications or click this link and scroll down till you see the Groups section and uncheck the boxes next to the options you do not want to receive notifications for.
Facebook should definitely have these notifications as opt-in rather than shoving it down your account. This is definitely going to create quite a privacy nightmare once again for Facebook.