Good in that it will be temporary: specifically 30 days.

Please don't preach about SEO if you know nothing about it or aren't up-to-date with how SEO works because, this is completely wrong. The penalty that Rap Genius have will be applied until their site fall backs into the Google Guidelines[1] and they help webmasters to get their site back in line with those guidelines through informing them what type of penalty[2] their site has.

This may take 90 days as it took JC Penney[3], 11 days as it took Interflora[4] or even 30 days. However, it should be relatively quick and straightforward for Rap Genius to recover from this penalty because, the penalty is based on links they've built themselves through their "tweet-for-links" system meaning that identification and removal of links should be relatively quick and straightforward.

  This is better than a fundamental algorithm change like Panda or Penguin because there's no coming back from those.

Again this is wrong. Essentially Panda looks at content and Penguin looks at links - both of which are within Google's Manual Action penalties[2] - and both of which you can recover a site from.

In order to fix a Google Panda penalty you need to completely overhaul your site to remove any rubbish content as well as, to improve the content. In cases where you cannot improve the content to add unique user value, you should completely remove it from the site.

In order to fix a Penguin issue, you should see my overview here: https://news.ycombinator.com/item?id=6963785 although essentially, you just need to identify the links which need cleaning up, try and get those links "cleaned up" yourself, submit a disavow file (if necessary) and then get Google to reconsider the site.

[1] https://support.google.com/webmasters/answer/35769?hl=en

[2] https://support.google.com/webmasters/topic/2604771?hl=en&re...

[3] http://searchengineland.com/90-days-later-google-lets-j-c-pe...

[4] http://searchengineland.com/interflora-gets-google-rankings-...