Receive Pingomatic pings and weblogs.com

Hi colegues!
I am programming an application that needs to receive pings of updated posts. I know that wordpress pings pingomatic, but what I really want is to receive pings from pingomatic or similar services. Does anyone knows how to do it? Maybe shoud we pay for this service?
Weblogs.com offers a similar service but there are lots of spam blogs. Do you know that if we use weblogs.com could we offer a good service? Should we install an rpc server?
Thanks for your support!
Fabian