I agree with iPotential: it's not a problem of Mountain Lion.
I'm actually using Lion with iSync (which I got from my old Snow Leopard Time Machine backup, but you can find it on the web, just like you can also find Front Row for Lion).
I've always used iCloud and everything was perfect. Two days ago I bought a Google Nexus S (now running Jelly Bean) and decided to have all my devices (iPod Touch, iPad, Macbook Pro and the Nexus) syncing to Gmail instead of iCloud, so that the Nexus could have the contacts too.
The first problem was that I had to erase all my Gmail contacts and try to import the .csv (with 560 contacts) manually from the MBP. This imported the contacts onto Gmail, but without the pictures. Then I synced the Android phone and got the contacts onto it. Afterwards I used an android app to get high-def pictures from Facebook for the matching contacts. These were perfectly synced to Gmail... but never to Contacts.
I tried adding a TEST contact with picture on the Nexus phone. It then passed the contact to Gmail. But the contact never got to Contacts on my MBP (Lion). I had to manually click the iSync icon to have it synced, but the pictures were removed. I tried erasing the contacts from the MBP and without warnings it erased everything on Google. The good thing is that my Nexus syncs every 15 minutes so I had enough time to export the phone's contact list to a .csv file, emailed it to myself, imported it to contacts on the MBP and re-synced with Gmail using iSync. Now I got pictures everywhere!
... but it was temporary. Now it's trying to erase all my pictures from the MBP too. I really don't understand it, and I can't think of any workarounds. I tried everything!
It's like Steve Jobs said when announcing iCloud: "it just works". It's a shame I can't use iCloud with my Android.