I suppose my earlier comment wasn’t exactly expansive, so I may as well elaborate. I’m not reporting any news by saying that the uptake of PHP5 hasn’t been explosive – over the past year, most of the big names in PHP-land have been commenting on it on mailing lists and elsewhere. The figures weren’t leaving much wiggle room either – 80/20 splits in favour of PHP4 were approximately what we were seeing.
Thing is, while backwards compatibility is a good thing in general, in specific cases like this one – well, it’s not that it’s not a good thing, it’s that it’s not really applicable. PHP4 and PHP5 are enormously different beasties and treating one as a slightly enhanced version of the other isn’t really valid.