Need your single post views to be totally different depending on what category the post is in? You can do this easily by creating special single post files for each category as needed, and then replace the code in your single.php file with the following:

if (in_category('jobs')) {
include(TEMPLATEPATH . '/single1.php');
} elseif (in_categorye('News')) {
include(TEMPLATEPATH . '/single2.php');
} else {
include(TEMPLATEPATH . '/single3.php');

Obviously if you only have one special category you won’t need the “elseif” statement in the middle.
Check the conditional tags reference in the Codex if you need to control the single post template by something other than category such as tag, post number, etc.