You made it to the final rounds of a job. Your one of 2 or 3 people, but "the other person" got the job.
Do not give up. Studies show that 20-40% of new hires do not make the first 90 days in a new job.
If the "other person" hired is not working out...you were one of the finalist before, you may be just what the hiring manager is looking for.
Be sure to follow these guide lines for ALL jobs that you do not get, but were in the finals for:
1) As soon as they say "no" or "we selected someone else", send a hand written note to the hiring manager...thanking them for the opportunity and that you know you would be a good fit with the company.
2) Mark down in your calendar to email this person in 60 days.
3) 60 days later, send this person an email. Let them know you are still in the job market and that you are still interested in working for the company. Thank them again for the initial opportunity and be sure to mention what kept him up at night (their biggest concern that needed to be fixed) and 1 or 2 other points from your interviews.
You never know what will happen...the worst...you will not get a reply (I bet that has never happened in your job search)...the best...they will call you back in for another interview to replace the person who is not "fitting in".
4) After the first 60 day period, stay connected to the hiring managers you interview with every 2 or 3 months. LinkedIn, professional associations, etc. They liked you and brought you in for a reason the first time. You may be the perfect fit the next time.