The new Wordpress 1.5.2 should finally fix the slow posting - caused by pinging - by moving the pinging to the shutdown, i.e. after the actual request-response chain. In German: with 1.5.2, pinging should no longer cause an eternal wait on the browser. It would be very nice if that actually works.
Since there are also security fixes included, an upgrade is generally sensible. Although WordPress, for a PHP application, functions surprisingly stably - but still, there are undoubtedly one or two skeletons in the closet.
Update: well, it hasn't really gotten faster when posting ...