The only way to deal with the unstructured nature of the "Who is hiring" posts is to have some sort of schema that can be processed. I also wanted to do something similar (imagine it with dc.js, for example!), but the data is too diverse.

A sample entry could be:

  company: 'Some Company',
  jobs: [
    {
      dev_type: 'Web/Mobile/Data',
      dev_sub_type: 'Frontend/Backend/DevOps/Android/iOS',
      visa: 'Required/Not required/Transfer only/Sponsored',
      remote: 'Yes/No/Maybe'
      locations: [
        'SF',
        'London',
        ...
      ]
    },
    ...
  ]

All posts could have a METADATA: compressed_json entry that can be processed by the site and displayed/filtered accordingly. Perhaps it could be built manually at the beginning until it catches up.