I haven't seen anything that was production ready yet.
Building a extension that allows you post public/private posts to yammer should be fairly straight forward. You don't even need a server side component to handle authentication.
If you have in-house web developers it should be a breeze
I have a client interested in pulling Yammer data down into QlikView. From your post above I gather that you did manage to extract some data over their API, but the problem was with downloading large amounts of data. Is that correct?
They now have a download function in their admin tools that can be used to download a bulk amount of data and can then be scheduled as well. It creates CSV files. I am interested to see how the unstructured Yammer data actually looks in a CSV format!!!
I get the impression from the documentation that only administrators have access to that utility. I asked their help line for clarification and hope to get something overnight.