The thing about these is that they are all, from an attack/ vulnerability perspective, pretty primitive, requiring user interaction--basically you're inviting someone to download a sabotage element onto an environment where most users (compared to PCs) don't find actually downloading and running an application to be particularly intuitive.

Basically, virus-wise this is stone age technology--while the actual platform and technical environment are new, the means required to get someone to expose themselves to risk and compromise are ancient. No doubt, someone somewhere will still be thick enough to download and run virus-infected attachments and programs, but you're nowhere near the armageddon levels of mass infection that would bring these things on the radar.