@_ck_ - Granted, I'd like to know more about the stats from Automattic, too. Did they just use a raw count of every blog that phones home? Did they do any adjustments for multiple blogs running from the same host? What about multiple blogs on the same host, but some are using PHP4 and some on PHP5? Did they lump all users at a particular hosting provider together? How many of those blogs currently on PHP4 already have the option to upgrade to PHP5 via their host's control panel? All these factors could affect the statistics.

And keep in mind also, PHP4 has been unsupported for, what, a year now? There are no more updates coming, not even security-related, for PHP4. And it's not like that news came out of the blue, hosts should have known about it and been preparing for it back then. I'm glad that WP is finally making a move to officially drop support for PHP4.