Refurbs are not likely to be the latest models. The price of laptops has dropped dramatically in the last few years -- so make sure you are getting good value, not just an attractive reduction on the original price.
In the US I believe some large dealers are given refurbed stock from brands like Toshiba. Others sell them direct from their own websites.
Some may sell via e-bay -- for example Canon UK sell factory refurb cameras on e-bay UK.