There's a new Chrome tag page (like the one there now that shows bookmarks) that you can "install" webapps onto your browser. Essentially, it's a shortcut center to the webapps you use. Then, there's the web store.
Clicking the web store icon will give you a web store where you can buy and install webapps. Then it gets added to your tag page for easy access. One example: Plants vs. Zombies.
Google also has magazines in their web store. First a demo by Sports Illustrated. (I think this is the wrong audience for sports talk.) How does it translate? It looks like a slideshow of the magazine's pages, where you can click to advance, and will have video and news and scores. No word on price yet.
They even have "enriched" ads, which looks pretty decent. For example, an ad for a camera will show various lenses that you can swap into a camera to see how it affects how you shoot a photo, updated live. Then if you want to buy the camera, it gives you a Google Map of local places to buy.
So what can you get if you build on the Chrome web store? 70 million+ active users. You also get this web store on Chrome OS as well as Chrome in the three OSes.
Special thanks to BorrowLenses!