Is there a Query Per Second limit for Yahoo Geocoding?

I am also interested in this question.  I am geocoding a few thousand addresses a day in a tight loop, and since about July I've been getting an error before reaching a thousand.

System.Net.WebException: The remote server returned an error: (500) Internal Server Error.

When I manually enter the URL that generated the error in a browser it works fine, and the next day I get a few hundred more before the next error occurs.  I would like to be able to geocode to near the limit (50k) (most days it would be far less) in a tight loop. Is the error being caused by an unpublished "burst rate" limit? If so, what is the acceptable rate?

Does anyone have an update on this.

I'm using PHP and calling about a thousand addresses in a loop and every 100 or 200 records the file_get_contents($request) call just times out. I've tried delaying it to every second but it's still occurring.

Is there some limit of requests per minute or something that isn't written in the documentation?

I am also having this issue when I try to process a CSV file.  Each row of the CSV needs to get a geo location. Is there a way to send a batch request and get a json array back with the geocodes for all the addresses I requested? This would allow me to make one call instead of being limited by trying to make too many in a short period of time.