+1 for baking
My bottles are already clean. All I do is load all my bottles into the oven (holds about 3 cases) and turn the oven on. Takes all of 3 minutes actual work time to sterilize 3 cases of bottles. Note that sterilization and sanitation are different. Palmer gives some temps and times for such things. The point is for minimal work the result is the best (IMHO).
If I had a dishwasher that would be quite tempting as well.
EDIT: here is the table:
Table 3 - Dry Heat Sterilization
338°F (170°C) 60 minutes
320°F (160°C) 120 minutes
302°F (150°C) 150 minutes
284°F (140°C) 180 minutes
250°F (121°C) 12 hours (Overnight)
and the link to the page