The number of apps has continually increased, there's a public API that can be used by developers and now the hardware is no longer available only in the US. "Chromecast is available in an additional 11 countries — Canada, Denmark, Finland, France, Germany, Italy, Netherlands, Norway, Spain, Sweden and the U.K," announced Google a few days ago. Google worked with local content providers, so you'll find many new apps that support Chromecast: BBC iPlayer in the U.K., France TV Pluzz and SFR TV in France, Watchever in Germany and more.
Chromecast achieved what Google TV couldn't do. Hardware was cheap and easy to use, content providers felt welcome, software was updated frequently. Google TV tried to solve too many problems at once, hardware wasn't great, software was rarely updated, content providers blocked the browser and didn't develop apps, few people bought Google TV devices. Chromecast did a few things very well and broke the cycle.
"Chromecast complements our Google TV efforts as a low-cost, easy device for consumers to watch online content on their TV without a new TV, new remotes or interfaces. Our partners still offer Google TV-enabled HDTVs and boxes that have the core functionality of Chromecast plus a rich, interactive Android experience," says Google.