Well it's been a year since our site got hit by penguin demoting pages for specific keywords. Over the course of the year we have attempted to correct the issues that presumably caused the manual action and as of yet have had no success regaining the ranking we had for the specific keywords.
Early on we launched a campaign to remove the inbound links that we created/had built. We were successful in getting about 90% of the links removed.
We submitted a list of all links that were created/built by us to google along with the attempts that were made to have them removed.
We removed directories/pages that had excessive inbound links. (for example, example.com/widgets was removed and the content was added to example.com/widget)
We did not use the disavow tool.
We did no link building since penguin was applied.
We have not yet seen any upward movement in the serps for the affected keywords, still ranking 900+ for the affected keywords and the pages that are ranking are obscure pages that should not be ranking for the keyword.
Also, when penguin hit we lost site links and those have not come back even for a search of the domain name (example.com).
With the exception of the site links issue I would think that we have not regained our rankings due to the fact that we have not done any link building since penguin.
We still rank very well for long tail keywords.