With GameStop’s incredible profits from the used market making digital distribution an increasingly enticing option for developers and publishers, GameStop’s acquisition of digital distribution service Impulse last April was no doubt a smart move to jump into that market before they got left behind. GameStop Impulse‘s launch today marks the juggernaut retailer’s attempt to join the likes of Valve’s Steam, Gamefly’s Direct2Drive, and EA’s Origin, which launched just 10 days ago and is a redesign of EA’s previous versions of a digital distribution service.

With two of the biggest fish in the games industry ocean branching into digital distribution, maybe now is the beginning of the download-dominated age long predicted by industry speculators. It also might be the beginning of the end for Steam’s dominance of the PC game digital distribution market, but I wouldn’t exactly expect Steam to just roll over and die. It’s also important to keep in mind that these services are for PC games foremost, although with Steam’s foray into PS3s and 360s and other distributors likely to try to follow suit, maybe GameStop’s days of brick-and-mortar stores really are numbered.

Not to be outdone by Steam’s recent 10-day “Summer Camp” sale, Impulse is offering its own limited-time-offer discounts on certain PC games as well. Dragon Age 2 for $40.00 and Fallout 3 GOTY for $10.00 seem like pretty solid deals to me.