In investigating OnFolio (thanks to Spike's comment), I found that I could give it a URL to a web service. In OnFolio, you can specify your blogger settings. It supports standard blogging environments like blogspot, or, it can take a custom command.
I created a web service that in turn calls SharePoint's Lists web service to create a new item in a SharePoint list (my 'Blog' list, in this case). I did this because the lists web service takes some fairly complex parameters in its "UpdateListItems" method.
My web service simply accepts a Title, Body and URL. It then formulates the correct parameters for the UpdateListItems method and calls the method on the proper WebService.
This is just a proof of concept and would require quite a bit of work to get it robust enough for the real world. For example, here's an issue that would have to be resolved:
The lists web service simply takes a ListName to know which list you are working with. Question is, which site contains the list you want to work with? That is determined by the web service you reference. If I'm working with a team site called "MyBlog," I would have to reference this web service:
http://servername/sites/MyBlog/_vti_bin/lists.asmx
If I want to work with a list in my “InvoiceProject“ team site, I'd use this one:
http://servername/sites/InvoiceProject/_vti_bin/lists.asmx
Well, if I want my web service to be able to post to any list in any site, we'd have to create a way to dynamically bind to the correct web service. Hmmm.....