When it comes to Google say it with me: Here we go again! The company is getting ready to celebrate another key milestone in August: its 3rd anniversary as a publicly traded company. Sure there will be the usual partying (especially if the stock keeps performing as it is today and stays above the nose-bleed $500 a share. (It opened at $85 three years ago, August 19.)

But three years is a magic number for another reason. Employees still holding pre-IPO shares will be completely vested on August 19. And there's a significant worry that these sudden millionaires will run for the exits as soon as they're able. That's a problem for two key reasons. One: Google could suddenly lose hundreds of key employees. And Two: A big flood of Google shares could suddenly hit the market.