I have been on these boards for several years and have never heard a single case of someone getting anything other than the latest gen macbook pro as a replacement for their current machine, ever. It has always been the latest model regardless of the year of the current model. There have been some times where apple has given individuals models with less vram which I and many others consider a downgrade, but otherwise they have always been at least as high end as the current unit (meaning a maxed out 15" from 2008 yields you a maxed out 15" i7 from 2011). This is just what i've seen. Results will vary.
I have also been offered a replacement machine which was two revisions past my unit.