home mining is definitely dead for majority of world because of electricity expenses. USB gadgets are fine to play with cgminer and linux, but they will not even ROI..
Home mining is for the most part basically dead unless you have free or near free electric. And the situation is going to get quite a bit worse in < 6 months when the block reward drops from 25/BTC to 12.5/BTC (*)
(*) If bitcoin price isn't well over $420-$450 by around 07-24 of next year it's going to get really interesting (not in a good way) in the mining community...even for the larger farms running the most efficient gear currently available! Particularly if bitcoin difficulty continues along it's current path.
anyone know what the chinese farms are paying on average for electricity ? this could get interesting....in north america...there are places with VERY cheap electricity...for example I pay 0.048...thats 0.036 US DOLLARS...When its over -12c outside.