This app sends the files to a specific email for a particular Kindle, not your general Kindle email address. It will also archive the files in your Kindle Cloud Library so you can download them later. And what's even better is that you can select DRM-free AZW and Mobi files and send them as is.
Now, this isn't an amazing new conversion tool. Yes, it makes it easier to send files via email, but it only supports the files that Amazon already converted for you (DOC, txt, PDF, RTF, and so on). But it does cut out a couple steps out of the process, which is nice.
And since it works as a printer driver, you can use it to send webpages to your Kindle. But I'm not sure that is worth doing; there are better options, including dotEpub (it now supports AZW) and Instapaper. Those 2 services remove all the ads and extra formatting that you don't want.
But still, it's a cool toy.