But more investigation, and it appears that something alters the trace. As args for the [0] element of the trace a what would be expected. Eg:

<?php

function errorToExceptionHandler($severity, $message, $file, $line)
{
    if (error_reporting() & $severity)
        throw new ErrorException($message, 0, $severity, $file, $line);
}

error_reporting(E_ALL & ~(E_NOTICE|E_USER_NOTICE));
set_error_handler('errorToExceptionHandler');


function divr($a, $b)
{
	if ($b >= 1)
		return divr($a, $b >> 1);
	return $a / $b;
}

try
{
	divr(1024, 2);
}
catch (ErrorException $e)
{
	var_dump($e->getTrace());
}

Generates..


array
  0 => 
    array
      'file' => 'C:\Inetpub\Framework\www\bug.php' (length=32)
      'line' => 17
      'function' => 'errorToExceptionHandler' (length=23)
      'args' => 
        array
          0 => 1024
          1 => 0
  1 => 
....

Expected behaviour.
No bug here.

How can the trace containing the function name of one function, and the arguments to another be expected?

This definately seems to be a bug... 

<?php

class AssertException extends ErrorException
{
	function __construct($script, $line, $message)
	{
		parent::__construct('Assertion Exception', 0, E_USER_WARNING, $script, $line);
	}
}

function assertToExceptionHandler($script, $line, $message )
{
	throw new AssertException($script, $line, $message);
}

assert_options(ASSERT_ACTIVE, 1);
assert_options(ASSERT_WARNING, 0);
assert_options(ASSERT_QUIET_EVAL, 0);
assert_options(ASSERT_CALLBACK, 'assertToExceptionHandler');


function test($a)
{
	assert('$a > 0 && $a < 10');
}

try
{
	test(11);
}
catch (Exception $e)
{
	echo '<pre>';
	var_dump($e->getTrace());
	echo '</pre>';
}

?>


Outputs

array(3) {
  [0]=>
  array(2) {
    ["function"]=>
    string(24) "assertToExceptionHandler"
    ["args"]=>
    array(1) {
      [0]=>
      string(17) "$a > 0 && $a < 10"
    }
  }
  [1]=>
  array(4) {
    ["file"]=>
    string(30) "C:\Inetpub\Framework\www\s.php"
    ["line"]=>
    int(24)
    ["function"]=>
    string(6) "assert"
    ["args"]=>
    array(1) {
      [0]=>
      int(11)
    }
  }
  [2]=>
  array(3) {
    ["file"]=>
    string(30) "C:\Inetpub\Framework\www\s.php"
    ["line"]=>
    int(29)
    ["function"]=>
    string(4) "test"
  }
}


Which seems off by one each line of the trace has the previous stack calls arguments.

Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

The trace only "skips" the error handler function, nothing 
else is "skipped".