BuddyPress.org

Works like a charm for me!

WP 3.0 and Buddypress 1.3 in two steps:

1) Make sure upload_path option is set to wp-content/blogs.dir/1/files
2) in old .htaccess change

RewriteRule ^(.*/)?files/(.*) wp-content/blogs.php?file=$2 [L] TO

RewriteRule ^files/(.+) wp-includes/ms-files.php?file=$1 [L]

Works!