'If blocks' documentation referred to: http://doc.silverstripe.com/doku.php?id=templates#if_blocks
It says in the documentation that currently negations such as x != 3 are not available. Does this mean that tests such as x == 3 are available?
Is it testing only on the presence of the particular property?
Can you test subproperty elements: eg. <% if $LinkingMode.current %> (stuff goes here) <% end_if %> ?
Things are looking up! :)