It's only available to the bigger firms representing Microsoft, though -- the 17 "premier preferred provider" firms doing at least $150 million a year worth of work for the company.

"We believe that diversity in our legal teams is a business necessity,'' General Counsel Brad Smith said in the announcement. "We cannot be effective if we cannot understand and appreciate the interests and needs of the incredibly diverse individuals who make up our stakeholder groups."

If the firms make targets set by Microsoft, they'll be eligible for quarterly or annual bonuses of up to 2 percent.

Here's how Mary Snapp, deputy general counsel, explained the targets, in the press material:

We created two alternative diversity goals, and each firm can choose which goal it wishes to use. The first is a 2 percent increase in the hours worked by U.S.-based diverse attorneys as a percentage of total hours worked on Microsoft matters, compared with the same time period last year. The second goal is a 0.5 percent increase in the total number of U.S.-based diverse attorneys employed by the firm.

Microsoft's internal legal group is pretty diverse. About 44 percent of the senior attorneys are women or minorities. Among the rest of the legal team; they number 50 percent.

To push things further, Smith also announced that 5 percent of the annual bonuses received by top managers in the legal group will be based on the outside firms' progress in the diversity program.

For a next step, they ought to lower the threshold so more firms could participate.