Blogrolling has opened up its own ping server, instead of reading Weblogs.com to alert updates.

I think this is unfortunate, if ping servers become a Balkanized mess this will cause confusion. One solution may be to federate the Weblogs.com server much like DNS, i.e. have updates propagate through a network but have Weblogs.com become the top of the tree.

I can't see any objection to this since weblogs.com is open and allows xml access.
The Weblogs.com ping server is potentially a crucially important piece of the web's infrastructure.

Blogrolling allows pings

Update - Dave writes that Weblogs.com can indeed be federated.