If the leak is at the steering rack then the seals are worn out.
The leak may become bigger and you'll lose more fluid.
If you lose too much power steering fluid and don't refill it, the power steering pump will run dry and it will be hard to turn the steering wheel.
Fix it as soon as you can.
You don't give any detail as to where the leak is. If from the rack then as stated by txn, it has bad seals. If so it's an expensive fix. There's a guy on E-bay who rebuilds steering racks, I installed one of them in my Civic because of a leak.
Ask where the leak was. Some have had great success rebuilding p/s pumps for $15-$30 (replacing the "O-rings" - which are actually shaped like a "D", sorta), do a search.
A replacement p/s pump shouldn't be more than $150, and isn't a difficult repair.
In my case, I fixed our leak for the cost of a foot of P/S hose and a hose clamp! My passenger side lower power steering PIPE (the part that leads from the rack to the p/s cooler) was rusting and developed a pinhole leak! That pipe is where road grit can get at it, and it rusted at the front edge, top surface of the pipe, where the hose connects. I was able to simply get a slightly longer p/s hose, clean the surfaces of the pipe, and replace the hose, clampign the end in the factory location, and again about 3" further up the pipe, sealing the leak with the hose. Total cost of repair: one foot of hose, a hose clamp, and about an hour of farting around.