[d3f]

For those wanting to do this with lighthttpd simply add the following code to your lighttpd conf.

Of Coarse editing the top line to include your forums domain.

$HTTP["host"]=="your.forum.domain" {
  url.rewrite = (
    "^/f([0-9]+)-([A-Za-z0-9\-]+)\.html$" => "/forumdisplay.php?f=$1",
    "^/t([0-9]+)(((-p)([0-9]+))?)([A-Za-z0-9\-]+)\.html$" => "/showthread.php?t=$1&page=$5&pp=10"
  )
}