Q: I've built a new datastore in GeoTools, and would like to include it in GeoServer, how do I do that?

GeoTools datastores are pluggable, so you just have to implement the right API and then just put the jar on the classpath. If you've implemented a datastore, you'll need a datastore factory that implements DataStoreFactorySpi, and a META-INF/services/org.geotools.data.DataStoreFactory file with the name of the datastore factory. If these are all in the same jar, then when the datastore is on the classpath it will automatically show up as an option in the web admin gui.

See http://sourceforge.net/project/showfiles.php?group_id=25086&package_id=129885&release_id=428086 for examples of pluggable jars (do 'jar xf' on the .jar file to see the structure and files contained, or just look at the source tree of GeoTools).