A few weeks ago I tried a stress-test beta for the service Gaikai. In many ways, the simplest way to underline how this works is to think of the On Live service of which we've been aware for some time, but focus on demos. The concept, as David Perry outlines in this blog post, is that gamers are known for one thing: in most cases they want to try a game before purchase. Which makes quite a bit of sense. A trailer for a movie gives you a similar experience. Sound clips from an album are a shortened version of what you'll hear. To try a game, screenshots and trailers only get you so far with the player; a large part of the appeal of games is that they are interactive.
Therefore, their goal is to offer these game demos to try in a browser. Upon completion you'd be directed to sources where you can buy it either through an online store, or digital distributor.
The big news is that they have signed up to work with EA. In fact, when I tried it, they were offering both Spore and Dead Space 2. For both of them, there were no problems whatsoever, and the games ran very smoothly.
Perry illustrates how this requires a bit of work on their end, as they have to engineer it so that transfer rates make it a smooth, seamless experience. The eventual goal is to have data centers in all major cities and provide the services directly from there. Then, they'd work with publishers directly.
In the same post, he further goes on to provide links so that you can try Mass Effect 2, Dead Space 2, Spore, and Second Life (some require a proper connection to one of their servers when visiting sites, so not all are available everywhere).
As Perry mentions, however, this is likely a service that will primarily be directed to games with a bit of hype at first. He goes on to encourage gamers to either send them suggestions of games they want to see, or contact the publishers and work with them so that Gaikai can provide these browser-based demos on the games' websites directly.
As a product, I can see how this would definitely be beneficial for PC gamers. While I'm sure there might be some crossover with console gamers, I'm not entirely sure how it will translate as an experience without the controller. Then there's the question of system requirements--playing it in a browser without a problem doesn't really tell me how my computer will handle the game, something I could at least test on a demo. Therefore, it's a service whose utility I can see, and I imagine it will have many metrics in place that allow publishers to see what does and does not work (tracking progress and such). As I've been fond of stating of late, though, more options tend to provide a more interesting landscape for us gamers.
Currently, the entire service is in beta, however, you can sign up on their main page if you have an interest.