Why am I getting a Chatter Digest email?
Since Chatter launched Monday - emails are automatically generated and send via your Salesforce Application. If your company is not using Chatter yet, these emails are not very helpful/useful yet - as the image above shows. If you would like to turn this Chatter Digest off for the time being, you can click the link at the bottom of the email. It will take you to your Chatter Email Settings that look like this:
Once your company adopts Chatter you will be able to see the value in the Chatter Digest and can enable it visiting the same Chatter Email Settings page.
Hope this helps reduce some confusion.