A Data Science Central Community
And the rise of the data scientist. These pictures speak better than words. They represent keyword popularity according to Google. These numbers and charts are available on Google.
Other public data sources include Indeed and LinkedIn (number of applicants per job ad), though they tend to be more job market related.
Feel free to add your charts, for keywords such as newsql, map reduce, R, graph database, nosql, predictive analytics, machine learning, statistics etc.