Get Posts by Custom Fields?

Is there a way to select posts based on a custom field?

For example, if I’m doing something like this:

$posts = get_posts(‘numberposts=1’);

can I do something like this?

$posts = get_posts(‘numberposts=1&customfield=x‘);

I looked at the get_posts() function and the query_posts() function.

What I want to do is add a custom field to one post called “featured”, set it to 1 on the desired post, and then be able to highlight that post on the hompage.

I also want to be able to select the 9 most recent posts that do not have featured set to 1.

Am I asking the impossible?