Definitely. I sat in on a Flash user group meeting last Wednesday (shouts to any FlashcodersNY folks), where Alan Shaw gave a fascinating presentation on prototype-based inheritance in AS3. One of the tricks he showed off involved having one class add methods to the prototypes of other classes at compile time -- to get the same effect with the Java-like static-typed OO that AS3 <i>appears</i> to encourage, you'd need a veritable bouquet of Command and Factory structures. Instead, sprinkling a little prototype stuff in among the traditional OO allowed this particular trick to rest all in one class.

The same thing applies in a lot of areas of AS3 -- you can write a GoF-y 2001-Java-looking app with self-documenting code and doc comments and blah blah blah, and then if it's convenient, you can ALSO use first-class functions with currying and all that geek stuff for statements like (just an abstract example):

newArray = oldArray.map(convertFrom(value)).map(applyTransform(transformParams)).reverse().filter(namesFromLanguage(Language.GERMAN));