From evidence of the value of social and mobile SEO to search traffic patterns surrounding Doomsday, May 21, 2011, the internet marketing community had much to buzz about during the week ending May 20.

One of the biggest news stories this week in social marketing – and beyond – was LinkedIn's IPO. The B2B-oriented social network's value doubled during its first day on the market. Its growing stock prices mirror growth in the site's B2B logins and usage, which may suggest to social marketers that it's time to get serious about promoting their companies on LinkedIn. As Brafton reported, the site even eclipsed Twitter in terms of unique visitors for a period at the start of 2011.

Nonetheless, Twitter is still key to social marketing, and the microblogging site generated headlines this week when it announced new privacy settings for users. Third-party applications are now required to be transparent about their data collection so users can opt out of sharing information about who they follow and what they retweet. Marketers who rely on analytics from consumer-facing third-party apps will want to come up with new ways to measure their Twitter ROI accordingly.

Another social network that made the news this week was Facebook. The social giant announced that Pages will now have Places functions publishing check-ins directly to branded Pages. This is good news for Facebook marketers looking to generate local user-generated content and word-of-web referrals.

Facebook also generated interest this week thanks to the announcement of Bing's “Friend Effect” search. As Brafton reported, Microsoft is now upping the ante with its social search options. Whenever users are signed into Facebook, the site will use friends' Likes as a ranking signal, display anonymous Like data for top results and promote “conversational” results. This should remind marketers of the value of sharing content with social audiences.

On a similar note, Google's social search was rolled out globally this week. International search marketers will now find their social campaigns can impact Google visibility worldwide.

The social search announcement was made via Google's new Inside Search blog. As Brafton reported, the new search blog serves as a one-stop shop for the latest search marketing news from the company. It seems particularly well-suited to help SEO marketers keep up with the latest content-oriented and algorithmic announcements from the company.

Businesses should be carefully considering how to push their content up in organic listings in light of news that blog marketing pays off. The recent State of Inbound Marketing report from Hubspot, relayed by Brafton, indicates that 57 percent of blog marketers gain new customers from branded blog content.

One of the biggest traffic drivers to marketing blogs and other online content this week was Doomsday-related content. As Brafton reported, search and social audiences can't get enough information about Rapture 2011 – with Judgment Day supposedly occurring on May 21. The subject is at the top of Google search trends and Twitter discussion topics.

Elsewhere in content marketing developments, news broke this week indicating that AOL is expanding local content production. The company will be hiring journalists to cover trending local topics in their designated regions, and local search marketers may consider following suit to attract traffic to their sites.

Content marketers might also want to remember to share their search-optimized articles through RSS, in light of a new development from Blekko. The company announced it will be fueling RSS search for Flipboard to help consumers find relevant content providers across the web.

High-quality content providers might also set their sights on Google News to increase brand visibility – but only if they're prepared to produce fresh content throughout the day. Google announced an auto-refresh option for Google News this week, which emphasizes the search giant's commitment to promoting fresh content.

Google also made some paid search announcement that relate to content. The company will now offer Google Instant previews for landing pages, which may drive clicks to the ads that lead to the most information-rich landing pages. Also, Google is moving display URLs into the headlines of paid search results to help consumers find the most relevant paid search results.

There was also good mobile news for Google – and Google search marketers- this week. Q1 2011 smartphone sales show Android is up. Additionally, Google announced updates to its iOS search app, promising faster performance and an improved look for search results.

Of course, Bing will not be overshadowed in the mobile search market without a fight. Microsoft is rumored to be buying Nokia, which could help the company gain a leg up among on-the-go consumers.

Mobile marketers will likely find that smartphones are better than tablets in terms of engaging on-the-go audiences. As Brafton reported, Nielsen data indicates that less than 5 percent of the U.S. population owns tablets, but more than one-third are smartphone owners.

Teens are among the heavy cellphone internet users. In fact, 21 percent of teens access the internet exclusively through their phones, and marketers targeting this demographic should plan campaigns accordingly.

Next week, marketers will want to see if Microsoft and Nokia do merge to form a mobile (and mobile marketing) super power. There should also be plenty of initial feedback for Bing's new Friend Effect-fueled search. Stay tuned!