Awesome, thank MicKr
Simon has over 10 years of experience in IT for financial institutions, utility and the healthcare sector. He's done everything from helpdesk support, desktop and server support and deployment, critical issue recovery and service and process management. He's now an Evangelist at Microsoft concentrating on how IT Professionals can embrace the cloud and consumerisation to deliver the best technologies and value to their businesses. Simon can mainly be found writing and blogging for Microsoft TechNet.
Sorry for the slow reply I've only just seen this. There isn't a way to launch an appx using PowerShell (actually you'll be able to find a script [metro-launch] on the web that can). Continuous integration here isn't really a problem since sideloading is a way to deploy the app for the end user. I'm not aware of any automated test tools yet for Windows 8 apps either.
Hope that helps, ping me back if not or I can help more.