I have battery-life issues as well: Often, the battery is depleted after two or three days of light use.
Using the BetterBatteryStats app, I found that two processes named “switcher” and “PowerManagerService” seem to prevent the device from going into deep sleep by hogging the kernel wakelock. I don't know what “switcher” does. “PowerManagerService” appears to be the kernel component of all partial wakelocks; here, the “surface drawing lock” seems to be the culprit, which seems to be related to the Kindle app.
From some cursory experimentation, the battery seems to last longer (that is, apps, especially the Kindle app, behave more civilized) when Wifi is on standby rather then switched off completely.