Just a short note to let you know that Spark is nearing release. A few of the features I mentioned will not make it to the initial release, as they require more fine-tuning, but they will be eventually included in subsequent releases.
I’m still receiving questions about why I ask for login information in gsDroid, and while I discussed the reason at length in the gsDroid FAQ, I should probably reiterate that this is because both gsDroid and Spark get their information from the Xbox Live site, which is password-protected.
As to why certain other applications only require a gamertag, the answer is that they have access to a non-public API that I do not. That doesn’t make my applications illegal per se, though it probably does place them in a grey area (much like some of my other projects).
As it so often happens, the issue in this case is ultimately the matter of trust between the developer and the users, and while I don’t expect anyone to take my word for it, as with any such program, if you have reservations about giving your login information to an unknown application, you should refrain from doing so.