Hi Justin,
Yes, you can execute BAPI and RFC functions from the gateway, it seems the Gateway system is preconfigured to use SAP Enterprise Service Workplace as a backend for the Netweaver Gateway trial.
This way, the data is housed online in the respective ES workplace systems and simply exposed via your gateway system. It is also possible to connect the system to your own backend/data source.
ES Workplace: http://esworkplace.sap.com
You can use this guide to configure/expose/consume your functions: [Content Deleted June 2013]
Paul
Message was edited by: Jason Lax