There’s been a tie between Android and iOS for two months straight on the recently funded Millennial Media’s mobile advertising network, and December finally named a winner—Android.  For the first time, Google’s mobile OS surpassed Apple’s as the largest smartphone OS on the Millennial network, with an 8% increase month-over-month and 46% impression share.  iOS has a 32% share in this market.

Android’s ad requests grew nearly 150% from Q3 to Q4 in 2010, with a massive 3130% growth since January alone.  If you break down the revenue generated by mobile apps in Q4 2010, Android took a 55% share, leaving 39% for Apple.  Thanks to Android’s 13% increase quarter-over-quarter, Apple can no longer stake the biggest claim on app revenue, even in the advertising realm.

Apple has, however, maintained its lead as the top manufacturer on Millennial’s network, where it’s resided for the last 15 months.  Thanks to a solid front from the iPhone and iPod Touch, Apple devices take the top two slots for mobile devices overall.

Apple’s ad requests grew nearly as much as Android’s at 12% (during the same period), with a 14% increase since January.  Not surprisingly, the iPad’s growth rate is much higher, having grown 280% from Q3 to Q4 in 2010.

While Apple retains its top positions for mobile manufacturers, HTC is close behind, taking the #3 slot with a 9% month-over-month increase.  Millennial notes HTC’s dominance in the Top 30 Mobile Devices Ranking, correlating it to its increased popularity.  HTC actually has more than a few devices on this list, including the Nexus One, HTC Evo, HTC Droid Incredible and the Desire.

As far as carriers go, Verizon saw a 2% increase in December.  This is likely attributed to the popularity of the Droid devices, and its expansive device selection, offering more than a dozen of the phones listed on the Top 30 list.  We can expect Verizon’s influence to grow as far as Millennial’s concerned, now that the iPhone will soon be counted in Verizon’s growing family of mobile phones.

Android’s rising influence in multiple sectors of Millennial Media’s network reflects its Market growth, which has seen a significant rise in available applications.  Android apps represented 55% of the Application Platform Mix in Q4 2010.

Gaming apps are still in the lead in Millennial’s network, with Travel and Vacation app impressions doubling quarter-over-quarter.  Millennial notes quite an evolution in this app category, with related apps launching features in time for holiday travel, including mobile boarding passes, travel updates, reservations and check-ins.

Music and Entertainment apps maintained the #3 position quarter-over quarter, with 22% of the impression share.  We’re likely to see a number of developments in this category, though, as television apps are the fastest growing sub-category with 259% growth in impression share quarter-over-quarter.

We’ve seen a number of instances in which online television has made significant gains these past few months, and the increased activity on mobile device reiterates this trend.  What’s interesting to note here is the wave of online activity being offered and replicated in the mobile realm, being incorporated into applications as well as mobile browsing, overall enhancing the devices’ capabilities for prime consumer use.