It does, but in their defense, there's lots of well made high-end brands that do not bother with THX certification. THX Certification and circuitry is popular in receivers; speakers, not so much. Anthony Gallo's for instance mention that they build beyond THX specifications but do not (AFAIK) get certification. Still an amazing speaker that is art as much as it is a piece of sound equipment.
Avantgarde acoustic is another that comes to mind.
For a suggestions beyond what BestBuy and Circuit City have to offer...these are fairly popular for home theater:
http://www.av123.com/products_category.php?section=speakers
Lots of bang for the buck.
If you want something a little more discriminating: Usher are incredible sounding speakers that I've heard personally and really impressed me:
Usher Audio
paired up with Nuforce digital amps is a very good combination.
NuForce
For a sub with lots of bang for little buck: SVS is worth consideration.
SVSound - Home