<adminhtml_sales_order_view>
    <reference name="content">
        <block type="core/template" name="test-1" template="test/template.phtml" after="sales_order_edit"/>
        <block type="core/template" name="test-2" template="test/template.phtml" before="sales_order_edit"/>
    </reference>
</adminhtml_sales_order_view>

<adminhtml_sales_order_view>
    <reference name="order_tab_info">
        <block type="core/template" name="test-1" template="test/template.phtml" after="sales_order_edit"/>
        <block type="core/template" name="test-2" template="test/template.phtml" before="sales_order_edit"/>
    </reference>
</adminhtml_sales_order_view>

[...]
<div id="order-messages">
    <?php echo $this->getChildHtml('order_messages') ?>
</div>
<?php echo $this->getChildHtml('order_info') ?>
<?php echo $this->getChildHtml('test-1') ?>
[...]