Imagick::getVersion

You may check your version like this:
<?php
$v = Imagick::getVersion();
preg_match('/ImageMagick ([0-9]+\.[0-9]+\.[0-9]+)/', $v['versionString'], $v);
if(version_compare($v[1],'6.2.8')<=0){
 print "Your ImageMagick Version {$v[1]} is '6.2.8' or older, please upgrade!";
}
?>

Since it's not clear from the documention what this function returns:
print_r(imagick::getVersion());
Array
(
 [versionNumber] => 1632
 [versionString] => ImageMagick 6.6.0-4 2010年11月16日 Q16 http://www.imagemagick.org
)

The getVersion function for the ImageMagick class returns an array, with two values, one linked to the key value of 'versionNumber' and another linked to the key value of 'versionString'. The version number provides a simple integer, while the string provides the actual x.y.z version number, the release date, and the URL for the ImageMagick site.
Today (May 8, 2012), when calling this function, the results are...
Number: 1654
String: ImageMagick 6.7.6-8 2012年05月02日 Q16 http://www.imagemagick.org
Last month (around April 15, 2012), when calling this function, the results were...
Number: 1654
String: ImageMagick 6.7.6-1 2012年04月09日 Q16 http://www.imagemagick.org
So, I'm not sure why the "Number" value has not changed, but the "String" value is definitely responding to changes in time.
The code for producing these results:
<?php
 // Author: holdoffhunger@gmail.com
 $imagick_version = Imagick::getVersion();
 
 $imagick_version_number = $imagick_version['versionNumber'];
 $imagick_version_string = $imagick_version['versionString'];
 print("Number: $imagick_version_number");
 print("<br>");
 print("String: $imagick_version_string");
?>