Sprint today dropped the price on a pair of smartphones, the HTC touch and the Samsung Ace. You can now get each of these devices for a $100 with a two-year contract.

This is yet another sign that carriers are wising up to the great increases in average revenue per user (ARPU) mobile Web and e-mail can provide. As smartphone users are more likely to purchase a data plan than other customers. So operators are dropping the cost for consumers to get on the smartphone bandwagon, in the hopes that they'll more than make up for it once folks get their devices up and running online.

Last fall, Sprint became the first carrier to the HTC Touch in the U.S. It original sold for $250 with a two-year contract and after a $100 mail-in rebate.

As with the iPhone, the main means of interaction between the user and the Touch is through its display, which measures 2.8 inches diagonally, sports a 240 x 320 pixel (QVGA) resolution and supports 65,536 colors.

Unlike the iPhone, the Touch is built on Microsoft's Windows Mobile 6 Professional operating system, currently a far more open mobile platform for which thousands of applications are available.

The Touch features HTC's TouchFLO technology, which essentially grafts an advanced touch interface onto Windows Mobile. As a result, it is supposed to be capable of recognizing and responding to the sweep of a finger across the screen. It is even supposed to be intelligent enough to distinguish between finger and stylus input.

Sweep your fingers across the display to launch an animated, three-dimensional interface comprising three screens: Contacts, Media and Applications. The interface can be spun by swiping a finger right or left across the display, providing what appears to be easier access to these features for consumers than a normal Windows Mobile interface for most.

TouchFLO also delivers finger touch scrolling and browsing of Web pages, documents, messages and contact lists.

As a Windows Mobile Professional device, the HTC Touch offers Outlook Mobile, Office Mobile for editing and reading native Word, Excel, and PowerPoint files, Pocket Internet Explorer and Windows Live. With it, you can view HTML-formatted e-mail and push e-mail in an Exchange environment.

The Touch measures only 4 x 2.4 x 0.6 inches and weighs 4 ounces. It offers both Wi-Fi and Bluetooth, and supports Sprint's high-speed EV-DO 3G data network.

There's a 2 megapixel with 5x zoom for picture and video, 64MB of RAM, 128MB of ROM and a microSD slot for extra storage. Sprint is bundling a 512MB microSD card, a format that currently tops out at 4GB.

Its Li-Ion battery specs out to last 200 hours standby and up to 5 hours of talk time.

The Touch supports the Sprint Music Store, TV, Radio and other exclusive content from the carrier.

As for the Samsung Ace, which originally sold for $200 with a two-year contract and after a $100 mail-in rebate, it is a tablet-shaped that can be used both in and outside the U.S.—typical of handsets offered by GSM carriers like AT&T, but rare for CDMA operators like Sprint. This world phone capability is, perhaps, the Ace’s most interesting feature.

So in addition to a Sprint-standard CDMA radio with EV-DO 3G data networking, the Ace sports a second, GSM-type dual-band (900/1800Mhz} radio for use when abroad.

Unfortunately, you cannot be get super fast cellular-wireless 3G (or even 2.5G EDGE) GSM data networking with the Ace in areas outside the U.S. That's because the Ace's GSM radio tops out at anemic GPRS data-exchange standard.

Like the BlackJack II, the Ace integrates a BlackBerry-like QWERTY thumb-keyboard and a 2.3-inch, 240 x 320 pixel (QVGA) resolution display. Because it runs on the Windows Mobile 6 Standard platform, the display is not a touch screen.

The 4.65 x 2.32 x 0.46-inch and 3.9-ounce smartphone includes 64MB of RAM, 128MB of ROM, and a microSD card slot for gigabytes of extra storage. There's also a 1.3 megapixel camera, 1300 mAH standard battery for around 4.3 hours talk time, and Bluetooth 2.0 wireless with support for stereo headphones.