Apparently they're not going with Simperium, but instead developing their own "advanced syncing mechanism" as Hering also talked about in his first post about the State of Instacast Sync:
One alternative would be to develop my own syncing solution and roll out my own server infrastructure.
There are two memberships available. A "Basic Membership" at $6 for 6 months and a "Senator Membership" for $10, billed once a year. A subscription will get you "early access, priority handling" and a "super secret newsletter with insider infos".
$10 a year is not even the price of a $0.99 app a month and it will get you a Senator Membership and help a develop making his work even better.
For those who already love the app and use it as their podcatcher of choice, that's the best way to help improve on it.
The syncing platform is scheduled for "later this year" with the introduction of Instacast 3.0.
More infos on Vemedio's blog post and here's the link to become a member.