I think every gen has had its defining moment for one reason or another.
Dark Ages -> 8 bit
Cartridge loading, game saves (albeit rare), some arcade conversions,
8 bit -> 16 bit
Defined graphics, clear sounds, some audio, some rudimentary 3d, introduction of CD's as media, proliferation of game saves as a standard.
16 bit -> 32/64 bit
True 3d, true CD quality audio and voiceovers, FMV and pre rendered goodness. Realistic Backdrops, interactive environments and sprawling levels and stories. The biggest leap imo, this brought gaming to the masses it was something adults could do aswell as kids (resident evil was born).
32/64 bit -> PS2 Xbox
Probably something of a golden age of gaming at least for my generation. The PS2 was a phenominal beast, and was astounding from day 1, many new games expanded the genres that were now staple. For better or worse these consoles formed the definition that most now accept for 'videogaming'. Xbox brought much needed competition and founded the modding movement that, illegalities aside, has pushed great home coders to open up consoles way beyond their potential, Media center was born with the xbox scene whether MS admit it or not. Gamecube performs admirably securing nintendos niche as the 'other' choice.
PS2 Xbox -> Now
Something of a mixed bag this gen. Innovation from nintendo yet again goes down well. The 360 implements firm goals for its online domination and both 360 and ps3 sport some formidable hardware. Graphics are starting to move toward the spectacular in a lot of genres, however innovation is somewhat stunted outside of nintendo HQ. Huge open ended worlds usher in a new era of RPG type gaming that can be applied to almost any gaming model. Games like spiderman 3, saints row, oblivion and test drive unlimited are testament to this advance.
Now -> Future
This may be the most interesting leap yet, or perhaps you might say it always is the most interesting one. Where will we go? What will become of gaming? It can only be expected to expand and eventually become something quite astonishing, 5 years? 10? 100? Who knows. But video gaming is well set to take over as the worlds most popular recreational activity. As compared to the proliferation of film, we have only just gotten colour, the sound is still mono and no one can act believably. By that rationale GoW was simply 'Gone with the wind', In as little as ten years we could be playing 'Gladiator'.