I personally think it's a good idea to use both. As someone else stated, at worst it's useless. For me, the best case scenario is, someone hacks the DB, now they have the salt for every user, but they still don't know the common salt because it lives in the script and not the DB. Just my 2 cents.
Totally agree with this article! There are very few instances where a signup is mandatory to "test the waters". At the very least you should be able to observe(not participate) an app/site/whatever without having to give credentials.
Every time I make something new, whether for myself or for work, conversion is the very first though. How can I eliminate text inputs, make less required, or eliminate them all together until the user feels it is worth their time to actually sign up? This is the question everyone creating these sites should ask.
It's incredibly frustrating to make it half way through the hoops on some promising website or app only to be confronted with the "sign up now" to get what you actually came here for in the first place and wasted 30 minutes creating, oh and where's your credit card? You can shove that right up your ass, i'm out, oh and pissed.
How this works is beyond me. I'd rather spend a week, month, year whatever making something better for myself than be bullied into signing up for your crap app.