Powerblading started as a form of transportation, but tricks were added when traveling from one place to another. As skate makers develop more advanced after-market frames, more grinds are possible (not just boot, but also H-block grinds). The larger wheels allows skaters to go faster, jump farther and travel to more places; thus, allowing for more creativity in the urban environment outside the skatepark.
Powerblading is different from regular urban skating as the aggressive hard boot allows for more tricks. While powerblading does still use the large wheels from urban skates, the style is a bit different.
Powerblading is the natural evolution of inline skating and will continue to push the sport forward creatively and involving the equipment.
Take a look at this video edit by Mathieu Ledoux for an example of Powerblading.