This is not quite an issue as much as a small warning.

I would advise users of refine by taxonomy to add a blocking in robots.txt or else thousands of additional pages will be indexed by search engines.

If used together with pathauto it'll cause multiple pages for the same content.

Therefore a blocking of the taxonomy pages in robots.txt is advisable:

User-agent: Googlebot 
# don't allow taxonomy directory to be indexed
Disallow: /taxonomy/

#Other search engine robots
User-agent: *  
Disallow: /taxonomy/

Please include this in the readme.txt file somehow.

I also posted about this in the search engine group: http://groups.drupal.org/node/14690