Note: I will delete any comments on this blog that detail or link to ME3 spoilers from the leak.
IGN has learned that internal story files from Mass Effect 3 have been leaked online and posted publicly on a Russian BioWare community site (Update: Game Informer claims that the story files were extracted from the leaked demo).
BioWare is investigating this new leak, coming on the heels of last week's ME3 demo leak, and Jesse Houston has posted the following on BSN:
“We are still investigating, but it appears that some internal story files have been leaked. Even though the information in those files is out of date and does not reflect the final story experience, we urge fans not to read them if they want to experience the purest form of the story in Mass Effect 3.”
Update: Per IGN, BioWare's Greg Zeschuk and Ray Muzyka stated in an interview that the ME3 development team is listening to feedback from the leak and they may make some unspecified changes to ME3's story as a consequence. Muzyka claimed that the leak was overall a positive event in that it attracted more interest in the game, despite BioWare's disappointment that the leak happened at all. He still encourages fans to avoid the leak if they don't want to see potential ME3 spoilers.