Some weeks ago I ask here http://drupal.org/node/20577 about OG and TA compatibility, because I was trying to use the both on my site. If I follow Moshe answer it appears that they are not, to say the least, very compatible ! Searchnig drupal.org about that shows that there are many requests about using together several modules implementing node_access api. And quite always, people are desapointed because they don't work well together and they need to choose between one or an other. This is obviously not a right way.
To come back, having TA and OG work together should be a great enhancement. It will give us control over whom can access node and whom can use this or this vocabulary to tag them witch will open doors to new applications.
As I don't know many things about php by now, I can't be useful in coding anything but I would be happy to make extensive testing.