I was just browsing a forum and someone asked about a PHP file they had found on the web. It has several spots like this in the code:
if ($REMOTE_ADDR == \"\"
To go into a little more detail, the reason that the braces are optional is that the syntax looks like:
if(CONDITION) BLOCK [elseif(CONDITION) BLOCK] [else BLOCK]
BLOCK can be a single statement:
foo();
or it can be a brace-enclosed group of statements:
{ foo(); bar(); }