Saving Images to the Shared User Photo Album using the UIKIT UIImageWriteToSavedPhotosAlbum() function:

void UIImageWriteToSavedPhotosAlbum (
	UIImage *image,
	id completionTarget,
	SEL completionSelector,
	void *contextInfo);

Usage:

UIImageWriteToSavedPhotosAlbum(
	[theImage retain], 
	self, 
	@selector(image:didFinishSavingWithError:contextInfo:), 
	nil);

// callback when saving is done...
- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo {
	NSLog(@"finished saving");
	[image retain];
}

No 100% sure if the image has to be retained. It also seems to work without retaining and releasing it… It takes about 3 seconds to save a 480×320 image on an iPhone 3GS. Feels a bit long…