Aha! So the reason why Google’s been downloading my Atom feed every five minutes or so is because they seem to have been indexing blogs like crazy:
It looks both are even indexing blogs regardless of whether they’re powered by Blogger or not. You can even get the search results as feeds too, which is great for keeping up-to-date on the latest blogs for a particular subject. You can read more about it here.
And, linked to my previous post about Google Toolbar Custom Searches, here’s the necessary registry file to install a Google Blog Search custom search button in your Google Toolbar:

My name is Tony Ruscoe. I have worked at Google since January 2010.
I can also be found and followed here:
This is my personal website. The views expressed on these pages are mine alone and not those of my employer.