It all depends upon the reason you were fired. If you were laid off or downsized, then future employers will not view your being fired negatively. However, If you were fired from your job for cause meaning that it was your fault, then being fired is viewed negatively by future employers.
Most future employers desire employees with a spotless work history and/or record. Being fired from a job is a blight on your future employment. You are seen as damaged goods by many employers. There is unfortunately still a stigma attached to being fired from a job. Many times, employees who are fired from their jobs oftentimes end up in worse jobs because of the negative reputation of being fired.
Yes, people DO obtain employment after being fired but it is a long, uphill battle. You will have to prove yourself over all again. Also, you will be under constant supervision because you were fired from your last job. In essence, being fired will be a negative albatross which will follow you. You will have to work extremely hard to overcome the negative stigma of being fired.