Which plugins to install to achieve wordpress.com commenting functionality?

I’ve noticed that wordpress.com improved their commenting functionality with 2 useful things:

1) When “Users must be registered and logged in to comment” is active (which I want) visitors can actually log in using their WordPress.com, Twitter or Facebook account (there are 3 small icons below the comment textarea). I’ve seen several “social” or “Twitter” plugins on www.ads-software.com but am not sure which one does both Twitter and Facebook for comment forms.

2) There is an option “Notify me of follow-up comments via email” below the comment form and in the settings, there is the “Show a ‘follow comments’ option in the comment form” option. Again, which plugin does that?

Thanks.