Macrumors made an interesting discover when digging into the beta version of the iPhone OS 3.0. In one of the file one can display the following capture:
It seems that the video recording function will be included in the future iPhone OS 3.0. however, it is unclear if it will be available for all iPhone models, including the previous ones, or if it will be limited to the new version to be released in June. However, it is almost sure, that the zoom function will only be supported in the future model, as previous ones did not sport a camera able to perform such operation.