Wow dude thanks for writing the app so quickly. What is the etiquette for sharing apps? Are you supposed to share source code too? I don't want to be rude by asking you for the source
I don't use twitter, but I was able to upload a photo to skydrive just fine after swapping LiveID's. Steps:
reset my phone with my own liveID
download bunch of apps from appstore
dev unlock/interop, etc
manually edit registry and change to my wife's LiveID (she has zunepass on her ID which is why I wanted to swap to hers)
upload to skydrive
login to skydrive app and see that picture is there on *my* skydrive account, not my wife's
So skydrive integration with picture hub/camera obviously stored my liveID and credentials somewhere other than the regkeys I edited. Most likely Twitter is the same way.
I presume the credential data is stored encrypted in some weird GUID key with no obvious pattern. Too bad there is no regmon/procmon tool like on Big windows, otherwise I could figure it out in a few seconds... Although somehow I doubt that you can use provxml to import export those keys to re-write encrypted credentials. That would be a pretty bad exploit.