Splitting TempDB into multiples files equal to number of CPUs

The article SQL Server tempdb Best Practices Increase Performance suggests that I should split tempdb into a number of files equal to the number of cores. So for 4 cores you get 4 files. > By having the larger number of files, you can increase the number of > physical I/O operations that SQL Server can push to the disk at any > one time. The more I/O that SQL Server can push down to the disk > level, the faster the database will run. With standard databases, SQL > Server can cache a large amount of the data that it needs into memory. > Because of the high-write nature of the tempdb, the data needs to be > written to the disk before it can be cached back up into memory. Though it sounds good in theory, is it really that good as a general optimisation? Is it something that may only apply for specific systems where IO is very high?