Despite the massive popularity of the iPhone, iPod touch usage is growing at a faster rate than its older cousin, according to Mobile analytics firm Flurry. The company said in an announcement through its blog that iPod touch session usage grew from 31% of all mobile devices to 35%, while iPhone's user session, while still growing, shrank in percentage terms from 57% to 50%.

Flurry also said that Android user sessions grew from 10% to 14% during the same time. While still dwarfed by Apple's iPhone and iPod touch usage, Android's user session usage is growing the fastest of the three platforms.

The company also postulated that iPod touch represents a more important piece of Apple's future revenue growth than the iPhone due to its ability to hook young users into the Apple ecosystem.

"While it is clear that the iPhone has significant short-term revenue value for Apple," the firm said, "Flurry believes that the iPod Touch holds more long-term strategic value for Steve Jobs and team. As all industry eyes look to the iPhone, the iPod Touch is quietly building a loyal base among the next generation of iPhone users, positioning Apple to corner the smartphone market not only today, but also tomorrow."

Graph courtesy of Flurry

User session data growth was similar when broken down for social networking use and for gaming. In both sub categories, iPhone still dominates, while iPod touch and Android are growing at a faster clip.

The last bit of interesting news from Flurry's blog post is that the company found Manga to be exploding on the iPhone platform in Japan, which is itself helping to further boost the iPhone's popularity in that market.

"Because comic books like Manga lend themselves more to brief sessions of reading than traditional books," Flurry wrote, "especially with their rich graphical treatments, it makes sense that Manga is expanding aggressively to the iPhone."

Japanese publishers have gone from releasing fewer than 30 Manga titles per month for the iPhone in July to just under 170 titles per month in October, a significant level of growth.