No, but it would be easy enough to code up (I would offer to do it for you now, but I'm waiting for my fixed N900 to come back to me by post).

In the mBarcode thread I posted a simple example of a Python plugin that wrote to a text file for someone, but I'm not quite sure about the status of the Python wrapper plugin in the latest version of mBarcode as the api has changed and I've not had a chance to get it working again yet.

Certainly a C++ plugin would be easy enough to write, just take a look at the existing plugins and feel free to ask.