I'm sure you've figured out that Google can do whatever it wants. Sometimes we care, as in the case of Blogger, and sometimes we don't, as in I've yet to meet anyone in the real world who has heard of Jaiku.
The good news for the browser effort is that there are pain points for Google to address with the Browser. Despite the efforts of Microsoft, Apple, and the Mozilla project, no one has gotten the browser quite right yet in the space that counts most - stability.
In the announcement in their blog, Google says:
Firefox was born out of competition. They felt like they could do IE better, and have. It looks like Google thinks they can do better than FF, and tomorrow we may find out.
Need something to do until then? Read the Google Chrome comic book introduction.