Yesterday’s announced merger between AT&T and T-Mobile could bring increased access to more smartphone platforms throughout the US, and more spectrum for mobile apps that are becoming the backbone of a fully functional mobile web.

Despite apps being the dominant feature in smartphone ads, we’ve only begun to scratch the surface of growth in the mobile applications marketplace.  The introduction of the iPhone and iPad blazed the way, creating entire new markets and devices for applications developers to write programs.  With the addition of Windows Phone 7 and Android devices, the apps marketplace is a $5.6 billion industry, expected to grow to $38 billion by 2015.

To reach $38 billion in sales, apps developers will need access to as many customers as possible, people who will buy programs to run on their mobile phones and tablets.   The merger fills in the gaps of AT&T’s phone network, expanding its network to 95% of the American population. The merger also allows T-Mobile customers to realize the full potential of their network, providing access to new products and services available at LTE speeds.

As we’ve reached this critical point of growth in the apps industry, the limiting factors moving forward are connection speeds and spectrum.   Developers want mobiles devices to be able to manage the same type of programs that users are accustomed to working with on their desktops.  Yet to date, the mobile web has been more promise than delivery.  With AT&T rolling out a true 4G network over T-Mobile’s spectrum, the mobile web we’ve all been waiting for will now be here.

AT&T has long shown a commitment to the smartphone market, boldly investing in the iPhone when it was widely considered a mistake.  Now the carrier also serves Android and Windows Phone 7 devices providing apps developers the widest range of platforms on the largest network in the country.  Given this history, developers are willing to give AT&T the benefit of the doubt when it comes to support for smartphones.

For applications developers, this merger will expand the marketplace providing more opportunity for growth.  Meanwhile the apps that consumers are clamoring for – that are the focus of smartphones ads these days – will now reach a wider audience.  That’s something the apps developer community has no problem supporting.