Depending on who you ask, platform virtualization (a la Virtual Server, VMWare, Xen) is useful, cost-effective, sexy, or all of the above. So it's no surprise that the world is migrating to virtualized environments in droves; however, in doing so, has anyone really considered the security trade-offs? How well are virtual guest machines compartmentalized/segregated from each other? Looking beyond single one-off vulnerabilities (although those do exist!), this talk will explore various under-discussed problems on how current virtualization and compartmentalization implementations are not as rigid and secure as everyone would hope. In some cases, the move to virtualized platforms has us coming full-circle back to many insecurities that were solved/mitigated long ago in equivalent non-virtual components. This talk will encompass multiple virtualization products, and will focus on simple, practical areas of concern (network problems, abuse of product features, etc.). Basic ethernet networking knowledge is recommended for portions of this talk; low-level hardware topics relating to virtualization (CPU capabilities/abuses, memory management) will not be addressed.