If you've purchased MoI v2 after May 1, 2014 you can receive a free upgrade to v3 by putting in your v2 license key here: http://moi3d.com/3.0/upgrade.php
You'll receive a new version 3 license key and download links for the installers right on the page there, please save your license key in your records for future reference.
Hi Michael T, I'll hopefully be able to get something done for that tomorrow. At first the official announcement will just involve updating the main web page so it's not really a particularly big thing to wait for...
The order links on the main web page have already been updated to the new v3 order pages though.