How much should a smartphone weigh?

In recent years, phones have gotten bigger and lighter. For example, the S4 stayed roughly the same size, albeit with a bigger screen, but got lighter. The same with the Note 3. The Nexus 5 is also lighter, but slightly bigger than its predecessor. Nokia launched the 925 with the biggest trump being the reduced weight and better design. The biggest loss was probably from Apple, when going from the 4S to the 5, despite the phone being visibly taller.

This year we're going to have a new generations of smartphones and OEMs are more than likely going to pack more things in an even lighter package. But how much is too much? What do you think is the ideal weight for a smartphone?