On a subdomain of our site we've put up a members-only section. For that we use Angsuman's Authenticated WordPress Plugin (http://blog.taragana.com/index.php/archive/angsumans-authenticated-wordpress-plugin-password-protection-for-your-wordpress-blog/).
Since a few days I'm noticing that it takes about a day before a new password is sent to the user after the request is made. I don't know if this started after the upgrade to WP2.1 or not. But last week a few users notified me of this problem. And I don't know where to search for the answer.