IMHO, Google's biggest problem is people who think Google has loads of problems.
For example, when Google releases a product that's certainly not perfect but at least as good as that of its concurrents (Buzz for example), it doesn't take off when people keep bashing it.
Is that any different from an unknown web startup?
Typically, you can't be "at least as good as a competitor" if you want adoption, you need to be 10x as good. I guess the difference is that with Google, people will pay attention to it but bash it, while at a startup, they'll just ignore it. Personally, I think Google gets the better end of the deal.
For example, when Google releases a product that's certainly not perfect but at least as good as that of its concurrents (Buzz for example), it doesn't take off when people keep bashing it.