Exhibit A: MIT's Billion Price Project is showing declining monthly rates of inflation since March (red line above), and mild price deflation for the month ending August 30, see chart above and Paul Krugman's post here.
Exhibit B: Paul Krugman also points to deflationary pressures for commodity prices - the chart above for the CRB Commodity Index shows that the commodity prices are almost 20% below the early May peak.
Exhibit C: The 10-year breakeven rate (one measure of the market's expectation of inflation based on the difference in yields between regular 10-year T-notes and inflation-indexed 10-year T-notes) has been below 2% for most of the month of September and is now at the lowest level since last October (about 1.7%), see chart above.
Exhibit D: Greg Mankiw points to the chart above showing the annual percentage change in hourly earnings, and comments: "The slack labor market has kept growth in nominal wages low, and labor represents a large fraction of a typical firm's costs. A persistent inflation problem is unlikely to develop until labor costs start rising significantly. Notice in the graph above that the period of stagflation during the 1970s is well apparent in the nominal wage data. The same thing is not happening now."
Exhibit E: Gas prices have fallen by 12% since the early May peak, and are now at $3.52 per gallon, the lowest price since last March (see chart above).