As a Robotics PhD student at Carnegie Mellon University, I took a Computer Vision course called "Advanced Perception." This Machine Learning-intensive course was taught by Alexei (Alyosha) Efros and my final project was all about detecting objects using a variant of Latent Dirichlet Allocation.
Jonathan Huang and I (Tomasz Malisiewicz) created these documents. So if you are into object recognition or just into bayesian hierarchical models you can check out these docs:
Detecting Objects via Multiple Segmentations and Latent Topic Models
Correlated Topic Model Details
You can also download some MATLAB code that Jon put up on the web:
fitting a Hierarchical Logistic-Normal distribution
You can also download our MATLAB Latent Dirichlet Allocation implementation (variational inference)