As a contractor (as well as previously being responsible for hiring both contracting and full-time staff), I know some of the little things that can be, shall we say, annoying about the process - like finding the perfect contractor to help, just a little too late.
Contract Availability is designed to plug a gap, of knowing exactly when someone is available, so that recruiters can have easy access to those that are looking right now - and not having to spend valuable time and effort contacting those that just aren't looking. Being able to see when people are available, and when they last updated their profile, as well as the key skills is incredibly valuable.
I've sometime gotten a dozen phone calls in a week asking if I was available, indeed any developer that knows their stuff will be in a similar situation. CA was designed to help the recruiters - and contractors - avoid those wasted phone calls and allowing the recruiters to find they people they needed as fast as possible, as soon as the contractor knows they are going to be available.
This page is inspired by slashpurpose.org