For everyone whose software doesn't support multithreading, a Ping-Cacher in PHP is linked. It probably still needs a MySQL database and presumably the ability to set up PHP cron jobs. Pings then don't go to weblogs.com, but to the Ping-Cacher. And it forwards them.
Hmm. You could actually run that centrally in one place, then others could use it too. Not everyone needs to operate something like that. Ok, I've put something together, it's running on my server. If you want to ping weblogs.com but don't feel like waiting for weblogs.com, you can instead simply send a weblogUpdates.ping call (same format) to http://simon.bofh.ms/ping/. That gets stored in a database (PostgreSQL, not MySQL, but basically the same script as in the link). Behind it runs a cron job that starts every 5 minutes and sends pending pings. I'll probably also build an overview page that's similar to the one on weblogs.com, so you can see the pings with me right away and also get their status displayed.