There's an issue with imagecache that if you run your website under SSL, imagecache still creates absolute URL's using http:// . This causes warnings in browsers like IE6 about insecure content. Yes, I know that IE is lame and probably shouldn't be complaining, but I feel that imagecache if it's going to provide absolute URL's should at least respect and create HTTPS urls.
The problem comes in the funciton imagecache_create_url in which absolute => "TRUE" gets passed. Not sure why this is going on, but I bet it's a hack so that imagecache will work in the exceptional cases where a full URL is required. Well this work around for that bug, creates the https:// bug and we should resolve this as well.
This is important to me as I will lose sales from stupid people using IE in my stores from these warnings.