So, basically, this is a browser, disguised as an application? We already knew that browsers now act as new layer between the Operating System of a computer and an application, and is not just for browsing through pages of content. A simple step like this might be a step forward to better integration between your desktop PC and the internet, and thus the differences between applications and web (applications) will fade even more.
In his recent article "Exciting web browser trends in 2010" Devindra Hardawar describes that currently only Google Chrome supports this (just use the "create shortcut" option on the upper right). And in fact, it is quite handy! Devindra says in 2010 more browser will support this, and I agree on that. It isn't a too big thing to implement, I guess.
The most importent thing is if the users will start using it. I did. I use Google's Wave for some weeks now, start Chrome every day to check my mail and found out it is very convenient.
This, in combination with products like Adobe's AIR will bring the internet closer to your desktop and perhaps will bring even Microsoft Windows, Apple OS and Linux closer together.