Over time I grew dissatisfied with T Party because so many people who attempted it found inelegant solutions: arrangements that fit entirely inside the box, but didn't resemble the intended solution. And it didn't exploit its three-dimensional design to accomplish anything new.
At the design competition Guile in the Box was exhibited adjacent to Tom Jolly's Little Window, another 4-piece packing puzzle handsomely crafted from manzanita and zebrawood. Above, puzzle enthusiast Bram Cohen is trying to fit together Little Window after he'd already finished Guile in the Box.
[EDIT] As the founder of Bittorent Corporation, Bram Cohen got a bit of nice press today here. It's so nice how well-connected everything is in the puzzle domain!