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Google gives Android users a way to install unverified apps if they worked hard for it(including waiting 24 hours)
(android-developers.googleblog.com)
This is a most excellent place for technology news and articles.
They want developers to share their IDs to have their apps on the play store. The limited groups is so hobbyist developers can still share apps without having to jump through those hoops and so the users don't need to go and enable sideloading, with the caveat that there's a call on how many users you can send it to it looks like.