I think wooden coasters took the crown in thi s decade, we saw designers take the coasters to new extremes which some thoughts wasn't possible! But we have also seen many new steel concepts, or concepts taken further like the vertical coaster, some new concepts in steel have failed though, such as Maurer Sohne's X Car, which never seemed to take off, I hear reviews about Universals Rip Roket ride is pretty muc haverage, we also saw the take off of "more than vertical" rides, although a hit with parks and the general public, now alot of enthusiasts get annoyed to see one go up! Especially in a well financially stable park :roll:
Next decade, I'm sure we're going to see even crazier concepts, and designers taking more extremes, I saw a programme once, and it had a section "rides of the future", and people were wearing protective clothing etc because rides got so fast, high and put you through things which could kill you wihtout the protective clothes etc!! But that'll probably be 2050 XD.