Do you actually have any rows in the database?
Does the URL match any of them?

Yes

For reference:

mysql> SELECT * FROM feeds;
+------+-------------+---------------------------+--------------------------------+
| id   | name        | url                       | feed                           |
+------+-------------+---------------------------+--------------------------------+
|    1 | Planet-PHP  | http://www.planet-php.net | http://www.planet-php.net/rdf/ |
|    2 | SOA Journal | http://www.soajournal.net | http://www.soajournal.net/rdf/ |
|    3 | PHP Weekly  | http://www.phpweekly.net  | http://www.phpweekly.net/rdf/  |
+------+-------------+---------------------------+--------------------------------+
3 rows in set (0.00 sec)

mysql>

Also the "Expected Result" was generated using a static query with no bound variables:

<?php
print "<pre>\n";
$db = new PDO("mysql:dbname=pdotest;host=localhost", "", "");
$db->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );

$url = "http://www.planet-php.net";
$stmt = $db->prepare( "SELECT * FROM feeds WHERE url = '$url'" );
//$stmt->bindParam( ":url", $url );
$stmt->execute();
while( $row = $stmt->fetch() )
{
    print_r( $row );
}
print "</pre>\n";
?>

Can you try changing your bindParam call to this:

$stmt->bindParam("url", $url);

Also, add a:
$stmt->debugDumpParams();
call after you prepare the query.

(the : prefix should work, just wondering if it is badly implemented).

Just removing the : has no effect.

When I added $stmt->debugDumpParams(); to it (after
$stmt->bindParam( "url", $url );) and hit reload the CPU maxes out
and Firefox eventually comes back with 577105 lines of:

SQL: [36] SELECT * FROM feeds WHERE url = :url
Params:  1
Key: Position #15:
paramno=0
name=[4] :url
is_param=1
param_type=2
Key: Position #15:
paramno=0
name=[4] :url
is_param=1
param_type=2

(those last five lines repeat until eof)

Jay

Can you try upgrading to the latest PDO packages and/or PHP 5.1.1?

I upgraded the PDO packages only and get the same result, with a caveat. When running "pear upgrade pdo" the last few lines were:

  Build process completed successfully
  Installing '/var/tmp/pear-build-root/install-PDO-1.0.2//usr/lib/php5/20041030/pdo.so'
  Installing '/var/tmp/pear-build-root/install-PDO-1.0.2//usr/include/php/ext/pdo/php_pdo.h'
  Installing     '/var/tmp/pear-build-root/install-PDO-1.0.2//usr/include/php/ext/pdo/php_pdo_driver.h'
upgrade ok: PDO 1.0.2
  Segmentation fault
  root@cochrane:/home/jay #

Running 'pear list' indicates:

  PDO                  1.0.2   stable
  PDO_MYSQL            1.0     stable

and the scripts run fine with non prepared statements, so it appears to have installed correctly despite the segfault.

I'll look into upgrading php to 5.1.1 later. I'm trying to keep this system as stock Ubuntu as possible, so it would be really nice if it worked with 5.0.5...

FYI from this page: 

http://bugzilla.ubuntu.com/show_bug.cgi?id=18167 

and those referenced from it I get the impression the problem is with breezy's 4.1.12 MySQL server package.  Prepared statements aren't working from Java either.  There's a workaround that works by providing a parameter on the connection URL; it works for my Java code, don't know if it applies to your case.

Unable to reproduce, and user comments finger the ubuntu mysql server package as being broken.