I'd never looked through this thread before but was surprised to not see http://www.backpackgeartest.org/

This volunteer-run gear review site does more than just gadgets, but it certainly includes them with sub-categories for cameras, communication gear, electronic devices, navigation & map gear, among others.

Certainly other forums are a resource, for example the electronics gear reviews on Whiteblaze, and at least a couple of sub-category reviews on BPL, such as navigation and photography.

Ultimately for me what's most interesting in keeping up with "gadgets" for the backcountry is just keeping up with geekdom in general via sites such as engadget.com or gizmodo.com. It's just hard to know when a "mainstream" gadget might seem useful to at least some folks in a backcountry setting. Smartphones and power supply options come most immediately to mind, but on occasion others too, such as eBook readers, and things like Eye-Fi which don't fit neatly into any one category slot. For most of these what I think is wanted is a more general (and good) review, where the reader just keeps the backcountry use in mind.