Tweets for Keynote and Tweets for PowerPoint can be downloaded from this page.
The latest version, as well as previous versions, are available below.
Download Tweets for Keynote: Tweets-for-Keynote-v1.2.zip
Download Tweets for PowerPoint: Tweets-for-PowerPoint-v1.2.zip
Download Helper Scripts: Helper-Copy-Image-Tag-to-the-Clipboard-v1.2.zip
Download Twitter Scripter: Mac App Store link
Twitter Scripter must be installed on your Mac in order to use Tweets for Keynote or Tweets for PowerPoint.