Currently the Social Pane enables users to add Activities to CRM records by clicking one of several buttons (Add Phone Call, Add Task) or Flyout commands (other Activity Types including Custom Activities). This is great, but there is little to no customization of the menu behavior itself (other than setting a default pane).
As a result, if we have a custom activity type (say "Inspections") it is permitted to add that activity to any kind of social pane-enabled record (i.e. Leads or Opportunities, etc.). This is a major issue for UI design, as it forces us away from the principle of "prevent user error" in those cases where activity types need to be restricted to certain record types. There is no way to do so without removing the social pane, and reducing the ease of scanning past activity details.