1. ($var and (my $foo = 'blah'));The second part of this statement will never be executed if $var is undefined. The 'and' is short-circuited, so the second part of the statement (the re-initialization of $foo) is optimized away never evaluated.
2. You are right. Poor use of the term "symbol table" on my part, since $foo is a lexical variable. I just got typing too fast ;-) However, I never meant to say that $foo was available outside of the block. What I meant was that it was initialized on the first call to mysub and retains the original value within that block since it is never re-initialized, just like using a sub to create a static variable as in perlfaq7. You can also get the same result (a static variable) by using my $i = 0 if 0;

On a side note, does anyone know of links/books/perldoc that I can look at which document this "feature"?

I think this feature should be spelled 'b-u-g'

And about strict not complaining, I was just plain wrong.

Update: Changed "optimized away" - Aristotle++.