Thanks!

For anyone looking for more info:

I edited this file: views/default/page_elements/header_contents.php

And added this code above the "display the title" line:

<div style="display:inline;float:right;"><?php echo elgg_view('page_elements/searchbox'); ?></div>

Did that work for you?

Sherri, vazco_mainpage plugin has search widget, along with many other interresting ones.