This appears to be new this morning, though links to this page appeared in the New Tab Page of both Chromium and the Chrome Dev Branch a few days ago. I thought it odd that Google would start putting out links to a page that didn't exist yet, but they seem to be rectifying that quickly.
Another thing I noticed is that the site is secured. Obviously they are taking the security of extension installing very seriously, just like Mozilla.
Of course there has been a great collection of Chrome/Chromium extensions over at ChromeExtensions.org for a while now. It seems there are a few new extensions added every day. My favorites: