There's no limit of posting but there is a limit of time interval of your posting. To see the time interval go through the "Beginner and help" section.
That information is in meta in this official thread:
https://bitcointalk.org/index.php?topic=178608.0What are the time limits on posting and the levels??
I know 360 seconds are for new people like me, but was wondering if there was break down somewhere on this.
waittime = 360;
if(activity >= 15)
waittime = (int)(90 - activity);
if(activity >= 60)
waittime=(int)(34.7586 - (0.0793103 * activity));
if(activity >= 100)
waittime = max((int)(14-(activity/50)), 4);