(They should have been steering clear of illegal P2P files on your business's systems and over your business's bandwidth anyway, but that's another blog.)
Some of those leaked copies deliver malware to your machines, along with the unlicensed 7.
The malware appears to be pretty generic scareware fake anti-malware calls which, one assumes, anyone looking for Windows 7 would know enough to avoid, but still...
Today's free availability of the Release Candidate (RC) direct from Microsoft should tamp down some of the demand for the leaked (and infected) copies, but there will still be those who take the BitTorrent route rather than "stand in line" for Microsoft's historically ... challenging (at times of high demand) servers.
Make sure your people aren't among those making that mistake. Microsoft's Windows 7 page is here.