Greetings all,
Here are my thoughts:

* Why would you want such a thing?
my ANSWER = "to create complex/nested data structures without cluttering up your script with single use variables: i.e. hashes of arrays containing hashes... among other things";

* What's the scope on an anonymouse thingie?
my ANSWER = "the scope is the same as with other named data structures, use strict and you will see any potential issues";

* Will they ever die/get lost/get clobbered?
my ANSWER = "reflect on my potential answer to the scope issue";

Hows that for short and simple.
Personally I use anonymous 'thingies' on a daily basis for nested data structures. Good scripting inheres in well packaged data... but thats just my opinion.