Just received a package consisting of two Snuglets http://www.newertech.com/products/snuglet.php and a removal tool. The Snuglet initially fits around the Magsafe 2 plug and when you insert it into the charging port, it's held magnetically inside the port. A considerably greater force is needed to unplug the connector.
Apple goofed with the Magsafe 2 setup: the plug wobbles around inside the receptacle too much and is much easier to accidentally dislodge than the original Magsafe 1 arrangement.
The Snuglet fills this "wobble" space.