Most Android phones ship with a microSD card to provide additional storage. While the card should alleviate the constraints of the relatively small internal storage of Android phones (megabytes of internal storage versus gigabytes of storage card storage) the reality is that the cards have limited value because you cannot install applications on the cards. The result for people who install a lot of applications is that they run into storage limitations, causing them to make decisions on which apps to keep on their phones.
Google appears to have added the ability to Android so that applications can be installed to and run off of storage cards. What that means is that most users will be able to install as many apps as they like, and that developers can release bigger apps, like games, that require more storage space. My one concern is that in my experience internal storage on most phones is faster than storage cards, so it may take longer for apps installed on storage cards to start up. Nevertheless, I think this is a good addition to Android that will enable users to gain full benefit of the phone’s storage card slot.