NERO 7 Ultra Edition has support for AVCHD/M2TS files. I was able to download their demo and open M2TS files from my Sony camera and convert to MPEG-4. Other output formats are supported.
The cost of the software solution to convert AVCHD is more than the Sony HD camera I'm using to film with! While this may convert the files to a more portable format it is not a practical solution.