Google CSE v0.1 Wordpress plugin
After you install (read the included readme.txt file!), use < ? cse_search_box(); ?> in your templates to display the search box. Please note that it may take a couple of minutes before Google updates its caches and your CSE starts working -this may be the case for any changes too, like adding or removing blogs from your blogroll.
As I said, this is still alpha. I'm looking forward to your comments.