Update: Instagram giveth, and Instagram taketh. We know the app supports multi-accounts for Instagram internally, but it's still not user-facing.
The latest Instagram beta appears to be enabling multi-account support from within the app, allowing you to switch between accounts without having to log out. This update is rolling out to beta testers in Google Play, so if you aren't a member of the beta for Instagram you won't notice any update. To join the beta head here and sign up, then check Google Play for an update.
It doesn't appear as though all the testers are getting the feature just yet, as none of us here at Android Central have been able to see it. If you are a beta tester and have multi-account support in the latest build, let us know in the comments below.
Source: Android Police