Separate to how useful this is, this is an awesome marketing technique that others should look into. That is, distributing a desktop app that's really just a front-end for what your Web app already does.
I've noticed it in myself (and I'm sure it applies to others) that I sense more "value" in downloading a "free app" versus using a free Web service. I was familiar with Litmus's services before, but I hadn't really bothered to give it a go until this. This desktop app makes it convenient (even though you have to use the Web to setup an account!) and it "feels" better somehow. If you have a Web app, think about whether a similar tactic could work for you (I've seen a similar thing happening with free iPhone apps promoting Web apps).
Pretty ironic, considering usually an argument for free websites over free desktop apps is that it's easier and less dangerous to try out a free website because you don't have to install anything.
I think it taps in to old assumptions. "Software expensive, Web free." On 37signals Live yesterday David Heinemeier Hansson was talking about how people take recommendations more seriously when someone is a paying customer of something than just a free user. I think this sort of thinking ties in with software being perceived as more valuable and why Alkaline could, perhaps, get better buzz than the underlying service.
I wouldn't be using this. Because static screenshots doesn't cover testing of dynamic behavior. For example when testing liquid layout I should be able to resize the window. Not mentioning testing hover effects on links or javascript effects.
Another big drawback would be the load times for the screenshots.
When I make a change in Textmate, I can cmd-tab into VMWare and refresh the browser in a couple seconds. I don't have to wait for the server to respond and download the images.
Static pages are pretty rare these days. Quite a lot of the cross browser issues are when it comes to dynamic content, so I'm not really sure how useful a single screenshot is.
You can download the XP images free from microsoft, ready installed with IE6 IE7 and IE8. You just have to jump a couple of hoops to get the images into a format virtualbox/vmware etc understand.
Currently time-limited to april 30, but so far MS continues to provide new versions. I guess they're just trying to prevent any other use of these images.
Was it really necessary to explain this with a video, with no apparent text FAQ or documentation page? Not everybody's work LAN permits video traffic...
Blog? Isn't that a little rude on their part? It's just happenstance that the "elevator statement" article is the current. If this like any other start-up blog in the future, later users who visit this page will be faced with marketing or development minutia. (It's why it didn't occur to me to even follow said link.)
I like the idea as far as checking for visual inconsistencies goes, but after trying out the free account I think it's just too slow to use on a day-to-day basis. Rendering takes too long, and switching between the different browser views even takes around 5 seconds. And as someone else pointed out, it isn't useful for any real testing of Javascript etc.
I've noticed it in myself (and I'm sure it applies to others) that I sense more "value" in downloading a "free app" versus using a free Web service. I was familiar with Litmus's services before, but I hadn't really bothered to give it a go until this. This desktop app makes it convenient (even though you have to use the Web to setup an account!) and it "feels" better somehow. If you have a Web app, think about whether a similar tactic could work for you (I've seen a similar thing happening with free iPhone apps promoting Web apps).