I had a script running fine under PHP 3.x and 4.0.0, but after upgrading to the latest version (4.04dev), I had some problems.  

Following is an example of the problem:

<?php
$string = "Test String";
echo "This is a {Test} {$string}";
?>

The code above when executed under an older version of the 4.x or 3.x series will produce the following output:

This is a {Test} {Test String}

but under 4.04dev it produces:

This is a {Test} Test String

note the the {} characters are missing around "Test String".  This is causing a problem in an SQL statement.  I have found that escaping the first { character will solve the problem, hence:

<?php
$string = "Test String";
echo "This is a {Test} \{$string}";
?>

will produce:

This is a {Test} {Test String}

Please note that only the initial { character needs to be escaped.

This is my first bug report to PHP and have the suspicion that this isn't actually a bug and perhaps a mistake on my part.  I know that the {} characters are used for delimiting code blocks, but I don't know what their significance would be in a string.  The fact that PHP will expand variables within strings (like perl) adds a little to the puzzle.  Since this behavior seems new to me I thought I would send it in just in case.