Sprint (S) customers now have Direct Carrier Billing through the Android Market, giving the option to bill the Sprint account instead of the default Google Checkout. It’s a feature that AT&T (T) and T-Mobile users have had since last year, and a perk for customers that like the idea of centralizing their phone-related charges. Direct Carrier Billing options are also friendlier payment portals for those without credit cards, and certainly makes it that much easier to spend a few dollars here and there.

Sprint-Google duo

It’s been a winning streak for the Sprint-Google duo. The addition of Direct Carrier Billing comes weeks after Google Voice made its app an integrated option on all Sprint CDMA phones. The inclusion marks another point of deep integration for two companies both appealing to consumers through customer service. And with carriers, credit card companies, banks, and online payment gateways all vying for their share of the mobile payments industry, Google (GOOG) is playing the entire field. [via Android Developers blog]

Android is also looking to penetrate the enterprise market, with a big push around tablets, and a growing gamut of software designed for business use. While the early tablets were manufactured by the expected bunch, Motorola (MMI) may be delving into the enterprise niche with a “rugged device that is able to survive life in the field,” Slashgear reports. The article shows a graphic with an Android tablet surrounded by business-centric capabilities. From software to batter life, connectivity and ergonomics, Motorola’s rumored tablet is feature-packed.

Android still leads, Apple gains ground

The enterprise market would be another big win for Android, but a strong tablet presence is a necessity for big gains. As tablets muscle in on the PC-world, efficiency-seeking managers will be keen on the many perks a tablet offers. With Android’s OS now leading the charge, it’s no wonder RIM’s (RIMM) PlayBook tablet will support Google’s primed platform.

In fact, 14 of the current top 20 mobile devices run Android, according to Millennial Media’s latest report. With Android leading with 48 percent of the smartphone market, promoting an Android device has become a savior for many manufacturers. The mobile marketing company goes on to demonstrate that the HTC (2498.TW) Evo 4G is the top Android phone, though the iPhone and BlackBerry Curve are next in line. As tablets become more popular, however, Apple (AAPL) gets another head start on Android. iOS is gaining ground on Android, growing 11 percent month-over-month.