Bryan Stopp - Platform Architect, AEM at VML will be presenting over the new few sessions on the following. These topics will likely run through the October meeting.
The Sling Stack Part 1 of 3: Apache Felix (OSGi)
This is a demo of the Apache Felix Project (OSGi). I'll describe the basics of how Felix works and then do a coding demo of a service which retrieves Account and Tweets from the Twitter API. 
The Sling Stack Part 2 of 3: Jackrabbit Oak (JCR)
This will be a demo of the Apache Jackrabbit Project (JCR). Again, start with an overview of JCR then dive into a code demo; using the previous session w/ Twitter API, we'll persist and then pull the info out.
The Sling Stack Part 3 of 3: Apache Sling
Demo of Apache Sling project. As expected: start with an overview of the Project, then dive right into a code example. Adding on to previous meetings, using the Twitter API code to create a REST service and HTML renderer for the persisted data.
Bonus Addon - Unit Testing with JMockit
Building on previous meetups & code, how to use JMockit for unit testing. This will take the code from the Sling, JCR and OSGi projects and create Mocks for unit testing.
This month's sponsor is RiverPoint.