multi-environment config for {siteURL} not working
Multi-environment configs require you to create a '*' config array, even if it’s empty because there aren’t any config settings that you need to set globally. Simply having that '*' array is how Craft is able to determine that this is a multi-environment config, as opposed to '.dev' and '.org' just being normal config settings. (See the warning on http://buildwithcraft.com/docs/multi-environment-configs.)

So this should work for you:

&lt;?php

return array(

    '*' =&gt; array(
        // It's OK if this is empty, as long as it's here.
    ),

    '.dev' =&gt; array(
        'environmentVariables' =&gt; array(
            'siteUrl'  =&gt; 'http://mysite.dev:8888',
        )
    ),

    '.org' =&gt; array(
        'environmentVariables' =&gt; array(
            'siteUrl'  =&gt; 'http://mysite.org',
        )
    )
);