There is a post in the forum today asking about how many posts can an application publish to a user’s wall or friends’ wall.
To be more precise, the post limit should be refer to the limit that an user has when publishing post via the application through Graph API (and I think that include the post published via old REST API too).
According to Facebook,
Based on the affinity users show for your apps use of Facebook Platform through their interactions, your app is allocated certain abilities and limits. This is the functionality currently allocated to your app. These values will change over time depending on how users interact with your app. All integration points have a set of limit values and the threshold bucket column tells you which of these limits buckets your app is in for that integration point. Bucket 1 is the smallest allocation bucket.
I get applications that has a limit of 40 requests per user per day.
To check the limits for your application, go to the “Facebook Insights Dashboard“, select “View Insights” under your application title and then select “Diagnostics” at the left hand column menu.