What you need to know - 05/20/11

Read about winners in LinkedIn's IPO and what it means for social media; Q&A with CEO of ReachLocal

Amazon announced that its customers are officially purchasing more Kindle books than all print books, hardcover and paperback included, combined.

All over the world, smartphones are continuing to conquer the mobile market and Android is leading the charge, according to the latest report from Gartner.

Jake Winebaum, former chairman of the Walt Disney Internet Group and the founder of Business.com, created Brighter.com, a site that lets consumers without dental insurance search for affordable and discounted dental procedures.

In celebration of the Chicago launch of Groupon Now, the company is announcing a huge promotion: $1 deals for hundreds of merchants all across Chicago.

Khosla Ventures, the firm started in 2004 by Sun Microsystems co-founder Vinod Khosla, is closing a $1.05 billion round for its new fund, according to an SEC filing.

On its first day of trading, LinkedIn's public stock peaked shortly before noon EDT at $115, and closed at $94.25, a full 109.44% above its starting price, for a market cap of $8.9 billion. Read about all the winners in the first public offering for social media.

And read about how LinkedIn is foreshadowing the rich social media IPO.

Check out my interview with ReachLocal CEO and co-founder Zorik Gordon, who will be speaking at next Thursday's Vator Splash LA.

Today's Entrepreneur is Paul Martino, Managing Partner at Bullpen Capital.