What does "regulatory genomics" mean?
The genome may be divided into two classes of sequences - those that code for proteins and those that do not. Those that do not code for proteins may be again divided into classes consisting of actively transcribed sequences that have biological activity (such as long noncoding RNA, microRNA, competing endogenous RNA and so on) and those that aren't.

These untranscribed noncoding regions may be involved in regulating the activity of protein coding and actively transcribed regions by binding to transcription factors or transcriptional coactivators/corepressors that control whether certain genes are expressed or not - this can happen close to the start of the gene (i.e, promoters) or far away (at enhancers). Distant enhancers can still affect gene expression because they and the genes they affect can be close together in three-dimensional space (The genome is folded in cells!). 

Regulatory genomics is, simply put, the study of these regions, which are called genomic "features" and how they regulate genes. A great example of studies in this area are offered by papers published as part of the ENCODE project http://www.nature.com/encode/#/threads