Personally, I see this as natural extension of the conditional block control which we already have for loops with CONTINUE WHEN and EXIT WHEN. This basically extends it to any block and it seems quite natural to have it for me...
This seems to me like a step in the direction of APL, where every statement is a conditional.
Perl has the option of putting the conditional on the end of a statement as suggested here for ASSERT. My experience has been that while it may "look prettier" to some, the conditional is overlooked in reviews, etc., more often than one would expect, giving a net loss in the overall risk/productivity analysis.
As a code maintainer, I would be opposed to adding something like this for no other reason than perceived aesthetics.
