In Japan they have cell phones with digital cameras built in. They promote them either for sending a photo to your friends cell phone, like instead of a true blind date you can send your pictures first. Or, you can catch a politician in the latest scandal and instantly send it to the news.
So, here's is about a month's worth of pictures. Of course I'd probably take more if I didn't always have my regular digital camera with me but then this is slightly less conspicuous.
It will be interesting to see how things progress because taking it all to an extreme you could (1) have a video camera in every cell phone (2) have a GPS in every cell phone for navigation (3) put the two together and at any crime scene, pull up the cell phone records and know everybody that possibly saw the crime and/or possibly filmed it.
My phone right now with out GPS will give me a list of generally where I've been. It can do this because the phone company knows which cell antenna the phone is talking to at any point in time. In fact there was a story that some wife thought her husband was cheating on her so she slipped a cell phone in his suit (note, they are small enough that you wouldn't notice). Then she checked where it at been when he got home. I don't know what she found out.