Market research firm EEDAR says that according to its findings Sony's Welcome Back program related to the PSN outage was a success.
The program, among other things, offered gamers two free PS3 games via download out out of a pool of five: Infamous, LittleBigPlanet, Wipeout HD/Fury, Dead Nation, and Super Stardust HD.
Using a sample of IGN users, EEDAR found that when factoring out the free Welcome Back games, 15 percent of the sample indicated that they'd bought a PSN title after service resumed – up two percent from March. The report noted that the free games also generated increased awareness for those franchises' respective sequels like LittleBigPlanet 2 and Infamous 2. In fact, those surveyed also said they were interested in Dead Nation 2, even though a sequel hasn't been announced. In response to its findings, EEDAR suggests that publishers could give away old games in a series for a limited time to generate interest in upcoming games in a franchise.
In general, EEDAR's report says that PS3's share of software actually increased one percent (not counting the free games). This is certainly a modest increase, but in light of the PSN outage, it's an interesting tidbit.