Not too far back we had some threads on the thermal fragility of glass
cookware. I don't recqll whether it was on r.f.c. or r.f.e, but
anyay there's a nice article on the topic in the latest (January 2011)
issue of Consumer Reports.

Some posters said that certain manufacturers had stopped producing
their wares in Borosilicate Glass and went back the the cheaper Soda
Lime glass, which does not tolerate temperature changes as well.
Worthy of note is that the Anchor Hocking company is named among the
guilty, as well as World Glass, who apparently bought some of
Corning's Pyrex plants (if I understood the article properly).

It's a good read for those who like cooking in glass, and might help
people avoid some bad surprises and painful injuries.

Alex