There's a reason why today's multi-feature cell phones are called "smartphones," emphasis on 'smart.' Many of these devices have more in common with a PC than they do a telephone. App installation? Check. Bright, luscious displays? Check. Webcams, QWERTY keyboards, and pico projectors? Check, check, and, um, well not just yet.
Integrating pico projectors into smartphones on the mainstream level is the next logical step, but it's a step that's still a ways off. According to DigiTimes, those in charge who produce pico projectors say the necessary R&D still isn't up to snuff and you aren't likely to see any kind of mass adoption until 2013 at the earliest. In case your calendar's broken, it's barely 2011.
It would be easy enough to integrate a pico projector into a smartphone, but the logistics don't make sense, These devices draw too much power, which is just one of the problems. Underpowered lumens and subpar picture quality are two other issues holding the technology back. And while we're listing out cons, you can throw price into the mix.
There are a few smartphones with pico projectors already built in, however these are exceptions to the norm, and they're not the slickest looking devices.