Well, 'you learn something new everyday' isn't just an old saying. I discovered ecogenomics today. Fascinating. Here's a short explanation:
Applications of genomics approaches have until now been restricted mostly to problems of medical science, pharmacology and plant breeding. We believe that environmental analysis and management can also strongly benefit from genomics approaches because environmental issues are often characterized by complex ecological interactions of diverse communities of organisms with the physical and chemical components of the environment.
So that's takes us part of the way to defining ecogenomics. I'll go find another one for comparison:
Microbes represent possibly the largest component of biodiversity, but lack of adequate tools for quantifying diversity, in either model or natural communities, has hindered progress in microbial ecology, especially microbial community ecology.
Genomics and modern molecular methods have dramatically altered this situation and will enable community ecology to address questions that are important scientifically and result in a better understanding of environmental issues. The integration of genomics with ecology will provide dramatic advances in all areas of microbial ecology...
...[and] will help us predict the effects of environmental perturbation on microbial communities. Such perturbations include the major features of global change, including modifications of biogeochemical processes (e.g., enhanced levels of CO2 and doubled rates of N deposition), land use change, acidification, desertification, ozone depletion, and climate change.
So, ecogenomics is pretty simply defined as "the intersection of ecology and genome science".
I suppose the name sort of hints at that...