cocos2d now supports Mac as a target platform!
Porting your cocos2d (iOS) game to Mac is really easy. If your game only uses cocos2d then the only thing that you have to modify is event handling code. eg: Replace accelerometer/touches code with keyboard/mouse code.
All the cocos2d for iOS functionality is present on Mac with only a few exceptions (see Release Notes). cocos2d for Mac also supports fullscreen and auto-resize.
cocos2d already includes Mac templates, so it is as easy to start a cocos2d Mac project as it is for iOS.
Remember that the Mac App Store opens on January 6, 2011
All the cocos2d API was converted from Pixels to Points. It means that cocos2d supports Retina Display automatically.
If you have a cocos2d game for iPhone and you want to support iPhone 4 (Retina Display), then the only thing that you have to add is the Retina Display assets (graphics and graphics meta data), and nothing more! There is no need to modify your existant code.
Do you want to improve the loading time of your game ? Then PVR textures is what you need
What is PVR ? PVR is a container format, in particular a texture container format. You can pack any texture format inside a PVR file, including RGBA4, RGBA5551, RGB565, PVRTC-4bpp,… texture formats.
PVRTC-2bpp and 4-bpp are supported since cocos2d v0.5.2, but since v0.99.5 it is possible to pack ANY texture format. (List of supported formats)
Why PVR is faster than .PNG / .BMP / .GIF images ? Because the texture is already in the desired format. There is no need to decode and convert the image to the correct texture format.
According to some performance tests, PVR files are loaded up to 8x times faster than .PNG files.
The only problem with PVR files is that they can be as 10x times bigger than the .PNG counterpart. In this case, cocos2d offers the alternative to compress the PVR files using gzip or a custom format, keeping an small file size (usually smaller than .PNG) with faster loading times.