On Pierre's blog, there's this great reminder of the progress being made towards PHP6, and some of the big leaps that have been made so far - specifically related to register_globals and magic_quotes_*

I really start to love the next major version of PHP (aka PHP6).

register_globals and magic_quotes_ have gone: #1 and #2.

The get_magic_quotes_gpc, get_magic_quotes_runtime functions are kept but always return false, set_magic_quotes_runtime raises an E_CORE_ERROR. It may help you to migrate (I was in favour to drop them all, but it was a too drastic change for my collegues :)

These changes and the GD cleanup (gd1.x and freetype 1.x support removed, some code cleanup) make me feel really better while working in HEAD that 5.x.

He also notes the recent demise of safe_mode as well.