To add something constructive to the whole battery discussion:
Besides the Tekkeon wallcharger, I also got their "TekCharge" battery pack (MP1550, $15 at NewEgg, batteries NOT included). Yesterday I loaded it with freshly charged PowerEx 2700mAh batteries. So here's the result (no stopwatch/by the minute count, sorry
Start with fully charged DR1000 (Solid green LED)
Light reading for about 5 hours (-> Red LED)
Attach TekCharge (Orange LED)
Continue off and on use through the evening while charging.
DR 1000 fully charged. Remove TekCharge.
Use a couple of bars while it's sitting around for a couple more hours.
Reattach TekCharge & resume charging before going to sleep (Orange LED)
Morning: TekCharge fully depleted, disconnected.
Continue using the DR1000 until completely drained (Red LED, shutdown)
Total: 12 1/2 hours (Yes, really)
Grand Total: 17 1/2 hours of light use
without ever turning the DR1000 off or attaching it to a PC or AC. Heavy usage will reduce that time, but I figure one should still get a solid 10 hours+
Sure it's not as elegant as a built-in solution (perhaps DIY soldered for the adventurous) but it is still pretty portable. It even comes with a little velvet pouch.
You can of course use it with regular batteries (which can be found in any airport or convenience store all over the globe). The beauty of using rechargeable batteries is that then the pack ITSELF can be recharged using the same cable and wallcharger used for the DR1000 (not at the same time
And of course, this solution can be used with any USB device: iPod, Sony reader, GPS... And there are other similar products out there that are probably as good. This is just the one I tried.
On a side note: in light of the usage time with this pack, the built-in battery does seem a bit on the small side...