We are absolutely going to open source these converters (actually: framework and config files with queries), but at this moment the code is too immature and badly documented. Our idea is to get some more conversions first so we can polish the queries and document the code as we go along. Expect it to go public in a few months.
Our strategy is to open source everything we build in addition to our core service, we have done that with the AdSense plugin as well.
One major lesson that we have learned in the past months is that we need a ‘real’ forum in order to make a good converter for it. So if you have a bbPress forum for us to convert, we’ll be happy to write a converter and add it to the list. For any well known forum system that we can add this way, we won’t ask for a hosting commitment in return.