Since version 2.1 WebForms features advanced permission system which lets you setup role permissions for each web-form.
- Enable "Display in menu" option on forms edit page.
- Go to System > Permissions > Roles and choose Role you wish to add permissions for the form.
You need to remove permission for "Manage Forms" if you wish to limit permissions only to forms of your choice.
- After user with the selected role logs in next time, his Web-forms menu will be updated, leaving him only what you permitted.