I'm using Grolsh bottles (the ones with the wire snap and rubber ring seal) which I rinse out religiously after each use and sterilise for an hour or so in the oven. After melting a few of the new (nasty) plastic tops I lowered the oven temperature to 200°F, which still appears to work fine from a sterilising point of view. No failures so far. Of course, those of you using normal 'all glass' bottles will be fine so long as you don't have the oven hot enough to melt the glass!