Ok, i'll bite.

The 15 minute (or 5, even) charge lithium batteries use a different chemistry that sacrifices capacity for power density, so that is not really what i want to see in my phone. It's great for making battery-powered motorcycles that burn up their motors and set speed records, though.

Lithium rechargeable batteries of one type or another are by far the most effective on an energy density basis, and not too bad on a power density basis either. Essentially the only way to get higher density than by using the extremely lightweight lithium atom (remember, it's element 3 on the periodic table, so you get lots of atoms (and electrons) per gram) is to use hydrogen (atomic number 1). Hydrogen isn't a nice compact solid like lithium, so until someone actually demonstrates a carbon nanotube adsorption approach that works at a commodity level, you have to use a form of it that is combined with carbon and maybe oxygen (an alcohol), and that means a fuel cell. Fuel cells aren't really appropriate for phone use, especially not the kind that can be made today.

In short, there are no rechargeable batteries that will last a week at the power draw of the N900. So what battery would you like Nokia to use?

Fortunately, we could make an effort as a community to isolate and eliminate the inefficiencies in the software to a degree never before done on a pocket computer. That's where we can make improvements. Figure out what really hurts your battery life and help work with devs to fix what can be fixed.