Yes - foam rollers (and deep-tissue massage in-general) are a vital fitness tools - deep-tissue massage is actually the only way to remove knots and create longer, smoother muscles, and it is best performed on warm muscles, prior to static stretching.
Foam roller deep-tissue massage can help...
If you aren't reaching new trigger points in your glutes, I recommend trying a denser deep-tissue massage roller (or even a lacrosse ball) - I use a 31" Regular Density RumbleRoller 90% of the time, and I also have a 12" Extra Firm RumbleRoller on hand specifically for my glutes :-)