In camera apps, is "zoom" a digital zoom, or an optical zoom? In some camera apps (native camera app in 2.2, Camera 360), "zoom" zooms in on the image -- filling the entire screen with a closer-in view of what you're shooting. In at least one app (Vignette [see below]) "zoom" shrinks the picture down. The latter behavior -- along with surely-lacking mechanical lens focus mechanism -- suggests that all of these zooms are purely digital, and not optical.



See Also:
Can a Dream's camera really zoom from the camera app? [device-specific question]
More often than not, Digital. Consider:


How in the world would the motor for moving a lens fit in a phone case? For that matter, where would the find the room to have variable focal length?
Would the manufacturers really put such a battery-drainer in the unit? How much more expensive would it be, too?
Should somebody actually come up with a phone with optical zoom, it would be a big deal and a huge marketing gimmick. ("The only phone camera with optical zoom!") I haven't seen any. Have you?


That's not to say that someday someone won't make hasn't made such a phone. There sure aren't any right now. Unless they make a big deal about the camera zoom, you can assume it's digital.