tedster - 12:44 pm on May 23, 2012 (gmt 0) [edited by: tedster at 9:55 pm (utc) on May 23, 2012]
Usually ignoring them is best. For sites that see concrete evidence that the scraper backlinks are impacting their rankings, then the solution seems to be sending stronger content ownership signals:
1. Institute authorship mark-up.
2. Use pubsubhubbub to sent "fat pings" to Google right when you publish new content.
3. Delay the standard RSS feeds for maybe an hour after publishing new content.
If you are sure you have a penalty, then a reconsideration request can also be helpful at times - however, true penalties seem to rare. Loss of authority and content ownership status is more common.
[edited by: tedster at 9:55 pm (utc) on May 23, 2012]