No problem.
Yes, it makes a noticeable difference under specific circumstances:
If you are reading from / writing to your boot drive and OS X starts paging at the same time. Obviously, being able to swap pages on a separate physical drive will eliminate the performance hit of the above scenario (as an FYI Windows allows you to do this through the GUI natively... Apple REALLY should have that option as well IMHO.)
THAT SAID: This upgrade / modification comes with some caveats.
#1) It is not for the casual GUI-only-minded user. If you aren't comfortable with / know how to get around in terminal as root user and know what and how to set permissions, users, groups, and don't feel comfortable rooting around the innards of your system: DO NOT DO THIS. If you accidentally screw something up even without meaning to (for instance, if you edit the above file with the wrong text editor you can screw up the permissions PERMANENTLY and Launchd will go into endless loop mode trying to mount the swap partition and keep failing to do so... rendering you with a very unhappy Mac)... you'll need to have the technical proficiency to figure out and fix whatever it is you might have broken. Unless you are ok with wiping clean and starting over if you screw up
#2) I really REALLY recommend using vi as the text editor... under NO CIRCUMSTANCES should you edit the file with a GUI editor as you will end up with a @ in the permissions which you can't strip out... this is a known issue with this "modification".
#3) Please make backups of all files before attempting to modify them. If I had to tell you to do #3, please don't attempt this modification!
#4) DO NOT BOTHER setting up a separate partition on the SAME PHYSICAL DRIVE THAT OS X IS INSTALLED ON!!!! You MUST USE a completely DIFFERENT physical drive to see ANY benefit from this modification at all.
#5) OS X doesn't entirely like this modification. Every now and then, even when it's set up and working... OS X will go into overload mode and freak out about the partition. A group of us are still investigating why this happens. After a few hours (it's happened 2 times in a month to me) it does it's thing and is happy again... basically... OS X at a system level ends up adding a NEW swap partition in the df table of the same name that you created, yet with a numerical appendage to the filesystem... for instance... right now... instead of "SwapDaemon"... OS X has created a new partition table called "SwapDaemon 0" and then about a day later DELETED the original "SwapDaemon"... although my mounted name on the Desktop is still the original "SwapDaemon". This is a work-in-progress modification... and does work beautifully in its current state for 99% of the time. However... obviously some other things are going on... so... just know what you are getting into before you go down this path!
And with that... I leave you all to your madness!

Cheers!