for my first beer i used the "alton brown method" of throwing a bag of ice in the bucket, and pouring the hot, near boiling wort through a large strainer straight into the bucket, melting the ice and quickly cooling the wort.
the bucket was fine (no damage, no melting) and the beer did not end up oxidized even after 6 months of aging. others have used this method for their entire brewing careers without a problem.
however, concerns about the possibility of:
a)contamination from the unboiled ice
b)melting plastic
c)a catastrophic near-boiling wort spill and
d)to a much lesser extent, oxidation
have lead me to change my process so that the wort is chilled in the kettle before siphoning into the fermenter.
a batch of beer is a big investment of time, and losing one SUCKS. if there's an acceptable way to minimize the risk i'm all for it. for partial boils an ice bath in the sink is cheap and easy to do.