Citrix was able to converge the management and infrastructure for XenApp and XenDesktop into one product with the release of XenDesktop 7. There are many benefits to having a single architecture and shared infrastructure between the two products. Not advertised, but I believe the most important benefit, is a common feature set and single development thread for both products. This will drive faster innovation and improve support. The product was XenDesktop 7, and new terminology for the supported workloads came to life as Remote Desktop Services (RDS) and Virtual Desktop Infrastructure (VDI).
But, meeting after meeting explaining this new design and introducing XenDesktop 7, clients would after respond with "I don't need XenDesktop, I am happy with XenApp". The marketing department at Citrix seems constantly busy with making product name changes, and I believe the change was likely tied to showing an uptick in VDI sales on Wall Street. The confusion hasn't stopped, and it seems the feedback has gone up the chain for the marketing department to make yet another change:
XenApp is back! Announced this week officially (http://investors.citrix.com/releasedetail.cfm?ReleaseID=821463), the product name is back in action as XenApp 7.5. The reality is that the product hasn't really changed as it is the same as XenDesktop 7.5. But now I can go to a meeting and talk about XenApp 7.5 and not confuse the diehard XenApp tattooed people that they are giving up on the server based computing they've come to love.
Welcome back XenApp, we missed you.