"Not on any linux distro, I believe ubuntu does not set any swap priority by default, some others might. You may call man swapon to the rescue ... here is an excerpt:
-p priority Specify the priority of the swap device. This option is only available if swapon was compiled and is used under a 1.3.2 or later kernel. priority is a value between 0 and 32767. Higher numbers indicate higher priority. See swapon(2) for a full description of swap priorities. Add pri=value to the option field of /etc/fstab for use with swapon -a.
As a side note, you might wonder why set swap default priority to 42, I believe it to be just another reference to the Great Answer."