[akz645]

Still works on vB 4.2.3. I spent 1 hour just testing all the features and I didn't encounter any problems.
My friend has this working on vB 4.2.2 PL 1.

http://i.imgur.com/a6mtKCQ.png
http://i.imgur.com/864gVei.png
Once you set up it up, press add and this is what you'll see:
http://i.imgur.com/vR0q0OC.png
Example: Usergroup: Registered users. Forum: Testing Post Count.
5 threads every 60 minutes in that forum section & 10 posts every 30 mins.
Note 1: You can not give double 'rules' to the same usergroup, in the same forum (sadly).
For instance, if I wanted to also limit 'Registered Users' in the forum 'Testing Post Count' with 10 posts every 2 hours & 50 posts every 3 hours -> I wouldn't be able to do that. If I tried, it would just replace my 'rule' from above.
^If somebody could implement that feature, that would make this mod perfect for me

Anyway, this is what you'll see now:
http://i.imgur.com/WOse60B.png
Now if you ever leave admin CP and want to edit later on, this is how you'd find it:
http://i.imgur.com/TZtZEkd.png
http://i.imgur.com/Vwq0lyy.png
Note 2: I just pressed Find, without actually specifying the forum. Hence all the 'rules' I've put in all appear. Putting the 'filter' via selecting a specific forum and/or usergroup works perfectly fine.

Note 3: I'd recommend testing out all these features too. Set it to something really low -
Example: 1 thread per 5 mins & 2 posts per 4mins.
http://i.imgur.com/GtFbtGl.png
http://i.imgur.com/5X2c1LF.png

Admin CP -> Settings -> Options -> Throttle Posts
http://i.imgur.com/lpL9KUo.png
Edit time for Thread/Posts.
Admin CP -> Usergroups -> Usergroup Manger -> [Select Usergroup] (edit):
http://i.imgur.com/D46dLkQ.png
Note: The times will be global. On usergroup manger, you can only specify the maximum posts/threads. You can't have separate times & posts/threads for each usergroup this way (you'll have to do it the other way- ' Per Forum & Usergroup Settings')
Note 4: ^That takes second priority. The settings from 'Per Forum/Usergroup Settings' takes first priority as long as you have this set to yes: http://i.imgur.com/jujjS13.png