FINALLY! The available formats include the newest VST3 as well as VST2 and AU.
See a session of 8 instances of OP-X PRO-II perform in Logic Pro X in this video trailer:
OP-X PRO-II - Mac and x64 release trailer
The available formats now include:
Windows:
VST2 32bit
VST2 and VST3 64bit
Mac: AU and VST3 32bit and 64bit
 
More infos are available on the release notes site:
Mac and x64 release notes
And the best follows now: We decided to offer the new versions to you for free!
We created a new user area where you can log in with your license data which offers all current installers, updates, infos, future upgrade and crossgrade options and links to resources related to your license:
http://www.sonicprojects.ch/userarea/login.html
The new Mac and x64 versions use a new proprietary host- and platform-independent patch format. By popular request the new x64 and Mac installers include ALL so far available sounds including all reloads in converted format- a whopping 2'500 patches in total! To convert your own custom sounds your user area offers dedicated patch transfer plugins.
 

Impressive! Thanks for the heads up!

If you have a problem downloading your update, you must get the ID correct, whatever email you used to register and then you need the serial number - then its FREE!
I know they got swamped today as 100"s of people could not get into the site to download (including me - wrong ID used!)
Got mine sorted, all downloaded but not installed yet.
If anyone has an issue PM me and I'll try and help
Nigel