I jumped the gun with saying Wordpress would automatically mirror the content I have here - it doesn't.
But there is a way to keep it up-to-date. It's a bit clunky, and manual, but it does work.
After logging into your Wordpress account, choose IMPORT from the the TOOLS menu from the drop down menus on the left side of the browser window.
Under the restart heading is a button titled RESET COUNTERS ONLY. By clicking on this, THE MAGIC BUTTON beside your already imported blog will change from SET AUTHOR to IMPORT. Keep clicking on the IMPORT button until the numbers all line up.
As you can see above, I have 658 posts in my blogger.com blog, of which 657 have been imported into Wordpress. I know this as when I click on the RESET COUNTERS ONLY button, it recounts for me. You can also see that I've had 1503 comments - thank you.
The one post that hasn't been replicated is this one. Wordpress also counts the drafts you have, and as blogger.com saves the posts while you're writing them, Wordpress picks that up and transfers it to the count. Cool.
So, once I've published this post onto blogger.com, I need to go over to Wordpress and click on the IMPORT button and 'Hey-Presto-Magico!' - the blogs will have the same posts available.
Clunky, not as nice as the import features onto the other places I have around, but it works. Anyone have a more automated way?