Identify a Twitter related plugin?

Hey guys,

I’m trying to figure out how to install this Twitter related plugin on my blog & need a little help figuring out what it’s called & how to actually install it. I’ve tried my best to find out but no success. I’m hoping one of you might be able to help.

The plugin looks like this (screenshot) and it opens up this page in a new window with a pre-entry of your website address. This is not my website but I found this plugin there.

Thanks in advance.
Chetan

[Moderator Note: No bumping, thank you.]