What's the process for getting a plug in in wordpress.com? Do they pick plug ins from the same directory as a local Wordpress installation? Is there any further approval?
We are considering making a Wordpress plug in but it only makes sense if people with blogs at wordpress.com can use it.
Check out the WordPress.com Plugin support article - it seems it really is a case of the WP.com team deciding which plugins have the green light, partly based on user suggestions and demands.
Are you talking about Wordpress.com or self-hosted Wordpress? I'd suspect it's difficult to get .com to accept and use a plugin, while there are millions of people who self-host Wordpress and can install any plugins they want: WordPress › WordPress Plugins