Brad Chen from Google just announced a new form of browser technology: Native Client. It will allow you to write C or C++ code which runs, through Native Client, in the browser.
"At its core, our release consists of a runtime, a browser plugin, and a set of GCC-based compilation tools."
With my Microsoft minded way of thinking, I read:
- a runtime which needs to be installed, like the .NET CLR,
- a browser plugin, like Silverlight,
- tools to develop like Visual Studio / Expression Blend.
Sounds to me like Google is a little worried about Silverlight and Flash and wants to play too 
Update [9/12/2008]: PC World refers to Native Client as Google ActiveX. It'll be interesting to see how soon the focus will go from computing power to animation power.