I was just looking at my Blogger API for PHP and discovered, to my horror, that it is an old RPC-based class I adapted from somewhere. I was right to suppose that their ATOM protocol must be fairly well developed and found on
the Blogger developer page a ready-made PHP class. Apparently, it's been around
since June. They even have
a wiki that lays out its usage all nice-and-easy, like I like. I'm going to start playing with this over the weekend.