While unpaind interns may be the norm in other fields, I don't know that I've ever seen an unpaid IT internship. Ours are paid pretty close to the hourly wage our entry level positions get.

My company takes on 5-10 IT interns every year for a six month commitment. While some of them don't work out, those that do have essentially gone through a six month trial period. If we do have entry level positions available at the end of that time then we have candidates who are known values.