Question: I'm using the Asana API and the "opt\_expand=." option when reading all the tasks in a project. It returns me a lot of information but not the tags. Is there a way to read the tags associated with a task?

Answer: 
(I work for Asana)

The API does not expose tags yet, but it is high on our list of features to add.
Asana's API now has Tag support (added June 19, 2012) <https://asana.com/developers/api-reference/tags>