1.5.2 – When is a ping sent ?

On publishing – Yes.
On Save – No.
On Save & Continue – No.
On editing a pblished post – Yes.
On publish to the future – Yes.

Can this behaviour be changed ?
There is a plugin that alters the ping for publishing to the future, otherwise the answer is No.

The above applies to 1.5.2 and could change for version 2.0