Tried using this plugin last night on our Multisite/Buddypress install.
It seemed to be working properly, with 2 major bugs.
1) Like another post in this forum, after you hit "Load more" posts, those avatars did not display a hover card.
2) The hovercard did not style properly. I was seeing the avatar and about 20 pixels of so of grey border to the right of it, which meant that I saw a TINY bit of the text data that was intended to display.
Unfortunately, the styling of the hovercard just broke, and it only showed this small portion of the card. The rest was cut off and would not display.