Getting a job flying for the airlines is very competitive and always has been. It has become even more competitive lately, and you have to do whatever you can to make your resume stand out from the other resumes in that big stack lying on the recruiter’s desk. Having experience flying an aircraft powered by turbine engines is a definite plus.
Aircraft that are powered by turbine engines are typically more complex than the General Aviation aircraft most people start out flying. If you have turbine time in your logbook, it shows that you have continued to train to meet your career goals. It also implies that you have been flying with more experienced pilots, at higher altitudes and at faster airspeeds. Turbine aircraft are usually flown on IFR flight plans, so it also shows that you would have been exposed to that relatively busy environment.
Having turbine time in your log book will also afford you opportunities to fly complex aircraft that you may not have the chance to do otherwise. Most decent sized airports have an Air Taxi or Part 135 Charter operation. Turbine powered King Airs are very popular aircraft for these operations, and if you have over 100 hours of turbine time you would even satisfy the operator’s insurance requirements and be eligible to fly in the right seat.
If you want to build turbine time, it is ideal for it to be built in to your flight training. This can be done at a few advanced flight academies. If you don't complete your training with turbine time in your log book, it may be expensive to aquire. It is worth the trouble to find a way to log some though if you want to stand out from your competition.