ArsTechnica posted a story that Apple listed an unannounced "Mac Mini (Mid 2014)" in a support document for its Boot Camp drivers and software for Windows
The Mac Mini is the only computer in Apple's lineup, vestigial non-Retina MacBook Pro aside, that hasn't gotten an upgrade to Intel's Haswell CPUs. Any mid-2014 refresh would be a significant upgrade, since new CPUs would give the Mini better CPU and GPU performance and reduced power consumption. Adding a better GPU and a Thunderbolt 2.0 port to the Mini could even make it a capable little 4K workstation, a useful capability given that OS X Yosemite has been "optimized" for high-density displays (Apple's words, backed up by our own observations).Mac Mini (Mid 2014) briefly appears in Apple support document