A new report from ad technology firm PubMatic says CPMs for inventory sold through ad networks are steadily climbing and have risen 35 percent since January. That should be good news for the industry, but the report has left some scratching their heads, while others are offering an entirely different analysis.

PubMatic's study touts the rising numbers as a sign that interactive's dark days are now in the past, thanks in large part to improvements in automation and efficiency.

Yet some say rising ad network prices are actually a bad sign, and proof that some publishers are still struggling to sell ads. Sarah Baehr, VP of media at Razorfish, believes ad network prices are going up because publishers are feeling the pinch and turning to ad networks to sell off their unsold inventory, according to a ClickZ report. Because these impressions are for premium websites, their price is usually higher, therefore driving up the CPMs of inventory sold via ad networks.

Regardless of whether or not PubMatic's report is the most accurate barometer of the industry, it's important to note that the study only examines prices for ads sold through ad networks, exchanges, and other brokers. The majority of online sales for premium publishers are still done in-house, according to Forbes.