The more things change...the more they stay the same.
Two and a half years ago, Mashable's key advice for building a startup was to plug into other audiences: Feeding the MySpace Beast. By creating MySpace widgets - embedded applications on the largest social network - sites could reach that "critical mass" required to stand up on their own.
Two of those featured companies - Photobucket and YouTube - saw huge exits. The others have achieved huge scale, but monetization has proven a challenge. Later, those same companies - sites like RockYou and Slide - would pull the same trick by plugging in to Facebook's platform.
Time for a refresher: the new "MySpace beast" is found in the life-feed - a bloodstream carrying content instantly around the web. Twitter, FriendFeed and Facebook Connect are all inlets into this stream. It's found, too, in the iPhone App Store, which puts your application in front of millions of iPhone users. And in Google's Android, a competing platform. All these hubs, yet again, provide audiences which can be siphoned off.
Startups need to realize that the game remains the same: if they build it, nobody will come. Why even turn on your startup until you've plugged it into a social power outlet?