are there limits to using embedded transparent swfs

Hello,

Well I now know how to make an swf's background transparent revealing the html below via:
  <param name="wmode" value="transparent">
(thanks lars)

does anyone know if there are certain browsers etc... that dont allow this to work? What are the limits? Does it work in Netscape, earlier versions of explorer, firefox, etc... what's the catch?

replies in danish are fine:)