Yes. I don't remember which use case I was thinking about when I suggested this, but it may be useful to e.g. write() all the data to a file object without actually making a copy (getvalue() does).
Thinking about it, I'm not sure this would be a good idea to do this by default. There is an ambiguity where it's not obvious if the buffer would contain the whole data or only the bytes after the current position. I think perhaps an explicit method (getbuffer()?) could be used to export a buffer-compatible object, without copying. Perhaps a memoryview; this would imply defining bf_releasebuffer without bf_getbuffer.
