In a recent interview with USCF (http://main.uschess.org/content/view/10007/571/), Jeff Sarwer said,  "I must say I love the type of chess played these days, it is exciting and breaks all the traditional "rules" that were so common back when I played in the 80's. Back then there was never so many "g4" type moves in almost every opening as now. I always knew that exposing the "safely" castled king and playing moves like g4 anyways for the attack was the way to go! If it works it works!"

Does anyone know which openings he's referring to?

I'm guessing he's referring to an increase in the number of high-level games and lines where White appears to be able to launch a kingside attack (with moves like g4) and get away with it. If you look back over earlier games in the history of GM chess, the original poster would contend you'd find fewer of these. I know that many folk often shuddered when Gary Kasparov would (all of a sudden, it would seem) launch a K-side attack with h4 or g4. So, this is my guess as to what the original poster is speaking to.

From what I understand is that GM theory now a days is solid variations and not vague principals. They basically took what Botvinik and others were figuring out in openings like the Winnawer (what french player would part with his black bishop on move 5 ?!) and applied it to everything. I beleive the g4 moves he is talking about are the pawn sacrifices for white in the semi-slav and phillidor defense.

There is also the Perenyi and Keres in the Sicilian Scheveningen, featuring a g4 early on to bring the game into fighting lines. An f3-g4 manuever is also prominently featured in the English Attack of the Najdorf Variation. Sharp chess generally results from this!

phillidor's defense!

This (the Shabalov-Shirov line) is without doubt the variation which inspired his comment.

There's also this line in the English:

So what would be the long-term (or short-term) plan in playing a move like g4?

Generally, when a move like g4 is played, it declares the players intension of forsaking king safety (in some cases, in others white has already castled queenside) and going for a kingside attack.