Editorial: Collaboration is an essential cornerstone of modern computing. Enabled by cloud computing, new wireless networks, ubiquitous mobile devices – to name just a few – the new collaborative ecosystem promises a potential that far exceeds our current capabilities. And as the world heads towards unlimited connectivity and global mobile computing, future collaboration solutions that fully realize this potential will require advances in networking, technology and systems, user interfaces and interaction paradigms, and interoperation with application-specific components and tools. As a nexus for collaborative computing, the Seventh International Conference on Collaborative Computing: Networking, Applications and Worksharing (CollaborateCom 2011) serves as a premier international forum for discussion among academic and industrial researchers, practitioners, and students interested in collaborative networking, technology and systems, and applications. In total, we received 62 submissions to CollaborateCom 2011. After a rigorous review and follow-up discussions, the Program Committee selected 19 papers for acceptance (a rate of 30 %). Following the completion of the conference, the Program Committee selected three of the best papers from the conference that best exemplify the themes of CollaborateCom and mobile computing for special invited submission to this issue. These three papers underwent a series of new reviews and revisions before appearing as you will find them here. In the first paper titled “Data Replication in Cooperative Mobile Ad-Hoc Networks: A game theoretic replication algorithm using volunteers' dilemma,” Hirsch and Madria propose a new replication scheme to strategically balance the constrained resources inherent in a mobile computing environment through a cooperative game theoretic approach. Nodes within the network collaborate via cooperative replica caching decisions to achieve overall improved query response times while reducing the query error rate and energy utilization. The second paper titled “Combining Mobile XMPP Entities and Cloud Services for Collaborative Post-Disaster Management in Hybrid Network Environments,” by Klauck and Kirsche presents a new system design that integrates portable devices and autonomous sensors through XMPP with the flexibility of cloud services to support post-disaster management. Through implementation and evaluation of two prototypes, they derive new insights into the practical application of XMPP and potential enhancements in hybrid (ad hoc and infrastructure) network scenarios. In the third paper titled “ChameleonSoft: Software Behavior Encryption For Moving Target Defense,” Azab and Elotweissy propose a biologically-inspired defense system that employs multidimensional software diversity to overcome the vulnerability of the persistent software monoculture. The system – ChameleonSoft – is built over a celloriented architecture, applying a multidimensional spatiotemporal diversity and hot shuffling of variants, hence effecting software execution behavior encryption, as well as adjusting its system policies at runtime to meet the continual change in the operational environment. As you read this issue, we believe you'll find that the selected papers make significant contributions to J. Caverlee (*) Department of Computer Science and Engineering, Texas A&M University, College Station, TX, USA e-mail: caverlee@cse.tamu.edu