I have some questions regarding Windows Phone 7. Where should I ask?
Regarding the title: Ask Android questions on android.stackexchange.com and bring your friends :P
Now there are sites or site proposals about using most smartphone platforms:
- Android Stack Exchange
- Ask Different for Apple devices (iPhone, also iPad, iPod, Macs, …)
- Unix & Linux for Linux-based mobile phones (Maemo, Meego, WebOS)
- Windows Phone proposal (targeting all versions: Windows Mobile, Windows Phone 7, and future versions)
If you would like a site about other platforms (Bada, BlackBerry, QNX, Symbian, …), create a site proposal.
All developer questions can be asked on Stack Overflow regardless of the targeted platform.
As mentioned in this answer, there's a Windows Phone proposal on Area 51, which has now gone on to public beta, meaning you can join the site and ask questions on it. As your question is about Windows Phone 7, you should use the 7.x tag, along with all other relevant tags.
If your question is about general programming with a windows phone, you can ask it on Stack Overflow with the windows-phone tag. As mentioned here, if it's about the Android OS, you can ask it on Android Enthusiasts instead. If it's about general use of the Windows Phone operating system, it would be on-topic for Super User.
So, depending on the question, you can ask it on Windows Phone, Android Enthusiasts, Stack Overflow, or Super User. Keep in mind that some questions may be on-topic for multiple sites, in which case you need to chose whichever one you think will work best.