Most of Rule 110's gliders seem to have been known at the time of Wolfram's World Scientific book , although Cook seems to be justifiably proud of discovering the ``useless'' glider gun and the highly convoluted H-glider, which he reveals to be the product of a three-glider collision. When his results were announced to Life-Mail, search programs were reported to have discovered his list of gliders and none others. Whether there are others is still a moot question; statistical considerations favor their existence (even after discounting complicated extensions of the known families), although it is evident that those which do will have to have longer periods and more complicated cycles than those now available.
Just having gliders doesn't do much for reaching the higher levels of understanding the behavior of a cellular automaton; the evident place to start the analysis is to study the glider collisions. Cook mentions such studies, but his report  did not include any of them,
Given a half dozen or more gliders, most of them with extensive variant families, the study of even the binary collisions is going to be long and laborious, although it does reveal some interesting patterns and regularities. These include the systematics of glider extension and reduction, and also some solitons.