It annoys the heck out of me that "works when you're offline" for most companies, including Google it seems, means "Without a connection to the internet". There's another kind of offline that is adversely affected by the first kind of offline, namely offline in the sense that I'm currently not at my own terminal. That means I'm offline in the sense that I have no context instead of having no conduit.
As data moves to the edges this does not get easier. The mass storage of GMail and similar modern webmail could be easily augmented to deal with this kind of offline as well, but that's not a focal point for any of the companies I can think of.
I think it's strange that it isn't for Google. Here's the one thing they have that Microsoft does not have more of. Servers. Microsoft is tied to devices I own. Google isn't - except that they are tieing themselves to these devices with e.g. the new Google Desktop.
So please Web 3.0 and 4.0 companies repeat after me:

I am not my terminal. I am not my terminal. I am not my terminal. I am not my terminal...