Hot on the heels of the old Unreal Engine going free to use, the new big-budget Unity 5 packing in all manner of features is also free for smaller projects. Unity 5 Personal is free for those on a budget of under $100K, but lacks advanced services. While many of the shiny features probably won't be supported by the Vita's ageing Quad-core ARM Cortex-A9, it can still show most mobile devices a trick or two thanks to its relatively low resolution and Sony's box of gaming tricks.
Several recent projects have promised Vita versions if Unity support allowed. I guess we'll have to wait and see if this affects Vita development at all, with pretty limited crossover from mobile and main console projects still the order of the day, whatever the codebase. More on Gamasutra. If any devs would like to illuminate us on the possibilities, I'd be delighted.