How can I stop LinkedIn popups on my iPhone?
4.2.2 has, due to customer feedback, added a setting under You and Settings (Gears icon) to turn off the Week in Review and all notifications that fall outside the normal notifications.

In detail, click the blue 'In' icon in top left corner of screen, then the 'You' pane, then the gear icon in the top right corner of screen, then set 'Notifications' to 'off'.