I was disappointed, crying, screaming, running around angry and banging my head against the wall when the video i/o functionality stopped working when I updated to the latest Ubuntu release (Jaunty). But since this is a open source world, I fixed this problem myself. Gentoo actually fixed this bug 1.5 year ago, so I used that patch and did some modifications.
If you are as frustrated as I am, don't seek any further. I made a Launchpad PPA for this new OpenCV package. I changed the includes to the new location and replaced the img_convert() function with the gentoo code as example. To install my packages open a console and run:
sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com cafc44ee7f39098ce6ec229cca70e6a9087475a0
after that add the following line to your /etc/apt/sources.list:
deb http://ppa.launchpad.net/gijzelaar/opencv/ubuntu jaunty main
After running a apt-get update you can install all the opencv packages, and they actually work.
By the way, if you use Python and OpenCV I advise you to check out the ctypes version of the python bindings. You can install them from my opencv repository by installing the python-opencv-ctypes package.
If you have any tips, comments or whatever please let me know in the comments.