I wouldn't. It's perfectly documented. See Re: 3-arg open() does not give warnings!?, even if somebody downvoted it. I wonder why!!

Update: I'm wrong, it's not "perfectly" documented. See Re^3: 3-arg open() does not give warnings!? (3 != 1).

Personally I find that an interesting feature and I even suggested adding it to

perldoc -q 'temporary file'
[download]

but now I see that it has never been added.