Click on this link below and it will take you to some of the 401(k) benchmarks. This will give you an idea as to what matching contribution formulas are used in the 401(k) industry.
http://www.401khelpcenter.com/benchmarking.html
It does not get specific into software companies. If your software company wants to recruit and hire the best software programmers I feel you will need to make the matching formula attractive. Since the stock market is so unpredictable, stock options may no longer help in recruiting the best people. You can use a generous matching formula as a recruiting tool. Hence there is no magic number. It all depends on your company environment.