Our software has been live since September with a Florida Ticket Defense Firm we have seen great traction and growth (400 clients in the last 90 days), and we appear to be on schedule to offer our software to law firms nationwide starting next month. I am not sure to date this could be defined as a success in the YC sense, we have had no funding, we have had no media coverage, no VCs on the board...but there has been local market adoption of our product and the potential to scale this seems attainable even if boot-strapping.
Edit: To be clear I am not saying YC defines success as funding, or media coverage...but show me a YC company that has achieved anyones definition of success without getting Funding and media coverage as a step along the way.