I've already written about a few cloud computing services here - Azure, SimpleDB, the Facebook data store - so I might as well continue down the list. Next up is Yahoo! Open Strategy aka Y!OS, a collection of services and APIs that let developers integrate their web applications with Yahoo. I've done a separate deep dive into YQL, the query language for Y!OS; I'll skim the rest of the platform here.

Y!OS is an umbrella that includes a number of different APIs and services. At a high level, Y!OS is similar to platforms like OpenSocial and the many gadget APIs. It allows third party web applications to be distributed, discovered, and live inside Yahoo. Y!OS apps may be installed by Yahoo users, run in various contexts on Yahoo sites, use Yahoo's custom markup language, integrate with Yahoo's social network, and access data from Yahoo's various properties, including private data - if permitted - via OAuth.

There are three runtime models for Y!OS apps: JavaScript via Caja, Flash, and traditional server side. Apps may be displayed in either small or canvas view, depending on the device and context. Both modes have a conspicuous Yahoo container, including a header, footer, and banner ad. That last part is notable, since there's no mention of revenue sharing.

Y!OS isn't really in the same league as full-fledged cloud offerings like Amazon Web Services, Windows Azure, and Google App Engine. It doesn't directly run third parties' code, nor does it host their data or static files. It's a more of a full featured web container and set of services. Still interesting, of course, just not my field.