Yeah, still not really feasible.They're basically wedged in there and there's only a few inches between the top of the keg and the top of the fridge. The real solution is to just get another keg and have a beer ready to swap in as soon as one empties.
Someone online modded a digital scale to weigh kegs in a kegerator and provide a digital output to a ARM SoC (e.g. Raspberry Pi)
http://scanlime.org/2010/01/hacking-a-digital-bathroom-scale/
I think the actual sensors are very thin and you could easily fit them under a keg, and have the output somewhere else.