It was a rumour and it was one of the 7 features I wanted on Instagram, and at last, after a long wait:
We can manage more than one Instagram account!
You can add the accounts you want through your Options:
One you have added your additional accounts, your username will look like a dropdown box by which you’ll be able to switch your identity. By now, you can add up to five accounts:
Isn’t it fantastic? Thank you, Instagram!