Exactly. from the About Google Trends page (the first question, no less):
1. How does Google Trends work?
Google Trends analyzes a portion of Google web searches to compute how many searches have been done for the terms you enter relative to the total number of searches done on Google over time. We then show you a graph with the results -- our search-volume graph -- plotted on a linear scale.
All this means is that people are using a wider range of search terms. (either from new terms entering general culture or perhaps people are just searching for more than they used to.)