It depends – and it depends on whether you have music purchased from the iTunes Store in the playlist.
Because of the DRM used in some iTunes Store music – and because Apple wants to play nice with music companies that help make iTunes and the iPod such a huge success – you can only burn 7 copies of a playlist with iTunes Store music in it to CD.
Once you've burned 7 CDs of that iTunes playlist, an error message will appear telling you you've hit the limit and can’t burn any more.
There aren't many ways around this besides adding or removing songs. A change as small as one song more or less will reset the burn limit to zero, but trying to burn the exact same playlist – even if the songs are in a different order, or if you’ve deleted the original and re-created it from scratch – is a no-go.