Currently I'm using NSThread to cache images in another thread.

[NSThread detachNewThreadSelector:@selector(cacheImage:) toTarget:self withObject:image];

Alternatively:

[self performSelectorInBackground:@selector(cacheImage:) withObject:image];

Alternatively, I can use an NSOperationQueue

NSInvocationOperation *invOperation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(cacheImage:) object:image];
NSOperationQueue *opQueue = [[NSOperationQueue alloc] init];
[opQueue addOperation:invOperation];

Is there any reason to switch away from NSThread? GCD is a 4th option when it's released for the iPhone, but unless there's a significant performance gain, I'd rather stick with methods that work in most platforms.