If you would like to move the currency switcher from the left column to the header, you can use the following instructions to do so!

Open /app/design/frontend/default/default/layout/page.xml
Locate:

<block type="page/html_header" name="header" as="header">

Change to:

<block type="page/html_header" name="header" as="header">
<block type="directory/currency" name="currency" template="directory/currency.phtml"/>

Open /app/design/frontend/default/default/template/page/html/header.phtml
 
After:
 
<?php echo $this->getChildHtml('store_language') ?>

Insert:
 
<?php echo $this->getChildHtml('currency') ?>

Save, Upload + Clear Cache
Make sure you have imported or manually entered your Currency Rates otherwise the switcher will not appear!
Its as simple as that!!