CHDK on the ELPH300 HS (Ixus 220 HS)
The Canon ELPH 300 HS is a new model released in March 2011, this means at the point of writing this post a CHDK release for this model doesn't exist yet. CHDK software needs to be rewritten for specific camera model released. This work is done by volunteers in their own time so it can take a while for a release to come out. You can see the state of development of CHDK for the new Canon ELPH 300 HS camera on the ELPH 300 page on the CHDK Wiki. For more detailed information about development you can go to the CHDK forums to see how the porting process is progressing. Searching the forums for "Elph 300" will return any posts on the progress of the port.