You're talking about a category of application which very few people are even using at the moment. Both Facebook and Google buy a lot of companies. They're not

You're talking about a category of application which very few people are even using at the moment. Both Facebook and Google buy a lot of companies. They're not "doing nothing", they're letting a small team try to develop something, which seems a perfectly appropriate reaction. How often has Google jumped into a totally new category with any real conviction? They half-heartedly launched Buzz long after Twitter was a hit, they killed Wave, etc.