This is way cool: if you connect to the Internet using WiFi, Google Maps 'knows' where you are and shows your location by default.
Slowly it is all coming together - the 'cloud' means that you can keep your data (and processes!) in one place, and you can access it (via WiFi) from anywhere, even using a lightweight client. Also both the client and the cloud backend 'know' where you are so functionality can be tailored to the time/location.
I'm not sure how much computing power is needed on the (portable) client - probably, only enough for rich media rendering. Other than specialized applications, most that an average user really needs should be easily done using a client that combines media/communication/lightweight computing services. I don't think iPhone is there yet (as the all-purpose 'client'), but perhaps a combination of iPhone and Kindle, three versions from now, might become just that.