Masked, has just appeared for preorders on both the Kindle and the B&N eReader/Nook. I don't see it in iBooks yet, but hopefully that's coming, along with other formats.
Once more, the Publishers Weekly review:
"Anders (Fast Forward) delivers an ambitious collection of superhero tales that provide top-notch plots and characterizations while honoring their four-color roots. In Daryl Gregory's superbly metafictional "Message from the Bubble Gum Factory," a former sidekick finally realizes the broader implications of superheroes. Stephen Baxter nicely applies hard science to the futuristic "Vacuum Lad." Gail Simone's "Thug" and Mike Carey's "The Non-Event" bolster predictable plots with solid characters and prose. Joseph Mallozzi's "Downfall" and Marjorie M. Liu's "Call Her Savage" embrace comics clichés and make them both more complex and more entertaining. ...Overall, Anders has assembled a solid anthology that provides first-rate entertainment. "