Google Reader is a absolutely fantastic tool for aggregating information from a wide variety of sources. It is even better if you are able to master the keyboard shortcuts.
Google has also included the ability to easily email posts right from the Reader interface which could be very powerful. But, it only works with Gmail. Obviously, Google wants to keep users on its various platforms, but it would be better if the user could choose which address they wanted the mail to come from. This is certainly possible as many other sites allow just that.
Most people wouldn’t want to send an interesting post to their boss, colleagues or customers using a Gmail address.