You could make your life a bit simpler than constructing the post data yourself, using HTTP::Request::Common:

return POST("http://www.BrilliantPeople.com/jobsearch.asp", [
    undef,
    # Search for Information Technologies stuff.
    hdnOccupationSelectionCodes => join(",",5118..5137),
    txtKeywords => 'programmer',
    # numberperpage => 100,
    # currentpage => $page,
]);
[download]

But that's just a sidenote. What I wanted to ask is did they change their site in the space of half a day? I can't find any form with a "hdnOccupationSelectionCodes" parameter there.

Makeshifts last the longest.