In regards to Hummingbird this headline from a recent Forbes article says it best:
[h=1]What Does Google's Hummingbird Update Mean For Your SEO Efforts? Nothing[/h]
In regards to the penguin 2.1 update - in a nutshell don't build shitty links! Update 2.1 further refined the link types targeted by the penguin 2.0 update that may have been missed. I'll link you to the original document, below, but here is the answer to the rest of your question in a nutshell:
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Of that link spam, Gabe said the following represent the culprits:
- Forum spam: This includes comments in forums with exact match anchor text links.
- Forum bio spam: Biographies of forum users containing exact match anchor text links.
- "Do follow" blogs: Blogs that don't add nofollow to the links posted. "Let's face it," Gabe said. "Being listed on do-follow resource sites can absolutely send Google a signal that you are trying to game links."
- Blogroll spam: Watch for blogroll links gone wrong. "Some may be fine," Gabe said. "If you are unsure which ones are bad versus good, ask for help from a seasoned SEO."
- Spammy directories: If you've used spammy directories in the past, and still have links out there, Gabe said "nuke them, have them nofollowed, or disavow them."
- Blog comment signature spam: Google seems to be targeting these links even when they're not followed, Gabe said.
Gabe also spotted a new culprit: classified websites showing up with heavy unnatural links leading to destination websites. He also said that, unfortunately, he has seen proof of http://searchenginewatch.com/article/2172844/Understanding-Negative-SEO-How-to-Defend-Your-Website rearing its ugly head during Penguin 2.1.
"I've had several companies reach out to me that are claiming negative SEO," Gabe said. "And after looking at the situation, I have to agree with them. And worse, I saw an entire business category (in a geo area) get hit with spammy links. That seemed very suspicious. All the business owners (who are competitors) were all blindsided."
[h=3]Tips and Recovery Recommendations[/h] It's business as usual on how to deal with cleaning up your site for the next visit from Penguin, Gabe said. That means downloading and analyzing the links, creating a plan of attack to remove and disavow as needed, and if you have to, remove pages (unless they're important).
Here are Gabe's top five recommendations on what to do if you've been hit by Penguin 2.1:
- Understand that Penguin heavily targets unnatural links. Your new content and social activity won't trigger a recovery.
- Thoroughly analyze your link profile, while keeping a keen eye on exact match and rich anchor text. That's what Penguin targets.
- Remove those links if you can, and disavow the remaining links. And use the domain operator in the disavow file when the domain is low-quality. Don't try and target specific URLs on a spammy domain, when you can nuke the entire domain.
- Make sure more unnatural links aren't being added as time goes on. Gabe said he's had a number of business owners think they cleaned up their situation, only to get hit harder during Penguin 2.1. After checking their link profiles, you can clearly see more spammy links were added during the spring, summer, and fall. This is what got them hit by Penguin 2.1.
- Move fast and be aggressive. Gabe said he has seen Penguin recoveries during Panda updates, so there is a possibility of recovery prior to the next official Penguin update"
Original link is from Search engine watch found here: http://searchenginewatch.com/article/2299665/Google-Penguin-2.1-Who-Got-Hit
If you need help with removing low quality links we have released a link cleaning service - just let us know if you'd like some details. We take care of everything from isolating spammy backlinks, creating the disavow file and reconsideration request and helping you submit those through WMT according to Google's method's of procedures for link cleaning.
Market Mongoose is refining our backlink profile for webmasters, resellers and agencies. We want to yin google's yang not fight them to the death

. Across the board the only customers we are seeing affected are those that had used SAPE links at one point in time or another from the wrong neighborhoods on the SAPE network.
Hope that helps!