We have been working recently on variants of BellKor's integrated model as described in their 2008 progress prize paper. We obtained results very similar from the published numbers: our implementation achieved 0.8790 RMSE on the Quiz Set (f=200), compared to the reported 0.8789.
This model proved superior to our own flavor of integrated model. However, what is interesting is that we were able to leverage the best of both models and combine them together. This combined model achieved a Quiz set RMSE of 0.8756 (f=200). This is, to our knowledge, the best reported number for a model without blending. On today's leaderboard, this would achieve the 47th rank by itself.