I just released v0.2 of Google CSE for Wordpress.
The new version includes a widget making it very easy to integrate the search box in you sidebar.
Other changes include:
- cse_search_box_tags() that if used in single.php will pre-fill the search box with the post’s tags.
-
automatically inserted in page headers. Of no use so far, but who knows? 
This is version 0.1 alpha of “Google_CSE” a Wordpress plugin that creates a Google Custom Search Engine using a Wordpress blog and its blogroll. (Read, my slice of the web to get the idea behind it.)
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.