Thanks to all who helped me out, nice one-liner indeed !
Off course you noticed its use for cgi :)
to dws: it should be save to asume that following ='s are url-encoded
if so we would need a function call to eg. url_decode() for the value. Hmm, url_decode could take two args change the second and return both, like this:

my %hash = map { url_decode(split /delim/, $_ , 2) } @line;
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other ideas ?