From TechDirt:

Both Microsoft and Yahoo failed to jump into keyword search in any serious way until long after Google established it as a giant business. At that point, both tried to play catch-up, with Yahoo buying Overture and Microsoft rebuilding its product — and  as we’ve also seen over and over again, by waiting that long, it was too late. The two companies still haven’t come anywhere close to catching up in market share, even if the technology is considered to be about equal at this point.

So the fear of some big company coming out and just “copying” you is generally overblown. If your idea is really disruptive, they probably won’t recognize it, and by the time they do, you’ll have a big head start, and their attempts to copy what you did will prove a lot more difficult than they expected.

How many newspapers are going to close because of the creative destruction of Craigslist?