One hackish way to do it is just embedding PHP in your blade template, at least in Laravel 4.0; I migrated an old project, poorly written, to laravel. Being so overwhelmed by the number of issues I ran into and time constraints I did not have time to look for a better way to do it. I did a bunch of html forms totaling about 30k lines of code.
<?php
$haystack=Session::get('orderInfo.form.conditions',array());
?>
Then you can access your data normally:
{{in_array('Special Assignments',$haystack)?'checked="checked"':''}}
That's what worked for me.
NOTE: Just adding my 2 cents for the sake of documentation. There are
better and cleaner ways to do it, as stated by the accepted answer.