If I were you I would start coding as if register_globals was switched off anyway!
PHP6 is heavily under development and as of PHP5 it comes switched off by default. If I recall rightly they have removed the ability to enable it completly.
While I will admit its nice but its a potential securrity nightmare especially if like me you tend to randomly open new varibles for holding tempory stuff (lazy I know
)
Its only takes a lazy stement such as
if (x==1) {
// do something bad
}
and then someone to come along and put x=1 into their browser. Not only does it help with security but its no harder using $_POST or $_GET. if you MUST use it for conveniance for example not knowing where your stuff will be coming from then you can write your own function to pull data out.