iPhone
iwebcamera
http://www.redmondpie.com/your-iphone-as-webcam-with-iwebcamera-9140802/

iPhone,BlackBerry, Windows Mobile, Pocket PC, Windows Mobile Smartphones, Symbian S60, Symbian UIQ 3
Mobiola WebCamera
http://www.warelex.com/

..and naturally I haven't found one for windows phone 7 - however I haven't really looked & I would assume there is something like that in the marketplace.

>I found this very cool app for Android called IP Webcam
>
>https://market.android.com/details?id=com.pas.webcam&hl=en
>
>What this app does (among other things) is allow you to capture images directly from the camera on an android tablet or phone over wifi via a simple URL.
>
>So if your android tablet/phone is connected to your wifi as ip 192.168.1.2 the IP Webcam app will give you various URL's to grab pictures with:
>Simple frame grab - http://192.168.1.2:8080/shot.jpg
>Full resolution photo capture - http://192.168.1.2:8080/photo.jpg
>Full resolution photo capture with autofocus - http://192.168.1.2:8080/photoaf.jpg
>
>As you can imagine, this is super easy to integrate directly into a VFP app.
>
>The IP Webcam application even supports running in the background which leads into the really cool part. You can use an application like Splash Desktop to remotely access a computer on your network which is running your VFP application. And now your VFP application can capture images directly from the Android device's camera!
>
>Now I'm trying to find an equivalent app over on the iOS side, but I'm not having any luck. Anybody come across something that offers similar functionality?