Wow! This is going to be torture waiting for all this to get done.
The given/when idea is very wonderful in a Perly kind of way.
I must confess that I've never been a big fan of try catch blocks (let alone nested ones); how they seem to move the core code further and further to the right. I always like that Perl could just take problems on the end. (... or die, ... || $foo = "bar"). Still, it's very nice to have that funcitonality in there.
I love reading Larry's respect for the humble origins of the language. Not force feeding a specific programming philosophy down peoples throats. Forcing stricter rules for modules and classes is a brilliant solution.