The Wolf Among Us Episode 1 product page on Xbox Live Arcade lists a release date of October 11.
The Xbox Live Arcade Marketplace has been shown to be a source of accidentally released, yet reliable, information in the past since the information is supplied straight from the publisher (Poker Night 2 was confirmed to be in development through XBLA).
So, chances are very high that the first episode of The Wolf Among Us will indeed be coming for Xbox Live Arcade this Friday (and to other platforms within a week of that, if the release dates of The Walking Dead are anything to go by).
Update: Green Man Gaming listed the PC version with a release date of the 11th of October as well.Also, IGN's Up At Noon has an interview regarding The Wolf Among Us and The Walking Dead Season Two, including footage of The Wolf Among Us in action.
Also, while on the subject of The Walking Dead Season Two, Telltale's PR person Laura Perusco confirmed that some time after the premiere of the first episode, Telltale is going to go ahead with their plan to have multiple seasons run concurrently by having The Walking Dead Season Two premiere while The Wolf Among Us season is still running.
Source: XBLA Marketplace