Where to find E.coli gene expression data?
There are some databases in which you can search for E.coli gene expression data:


GenExpDB: E. coli Gene Expression Database
Many Microbe Microarrays Database (M3D): A resource of microbial
gene expression data
Stanford MicroArray Database (use the search tool to find relevant organisms)
Colombos (COLlection Of Microarrays for Bacterial OrganismS)
ArrayExpress


To find out about the purpose and the conditions of the experiments behind this data sets you will have to read the respective publications.