Verizon Wireless has finally gained a foothold in the iOS space with the launch of the Wi-Fi only version of Apple’s iPad in retail stores later this month.

AT&T will also begin selling all three iPad models with Wi-Fi and 3G connectivity through its retail stores. The 3G version of the iPad already runs on AT&T’s wireless network, but the carrier has not offered the tablet through its brick-and-mortar locations.

Both carriers will begin offering the device on Oct.  28.

Verizon is offering a discount to customers who buy the iPad and Verizon’s MiFi personal hot spot as a bundle. The MiFi allows users to connect to Verizon’s network in areas where Wi-Fi is not available, since the version of the iPad to be carried by Verizon lacks the CDMA module necessary to connect to the operator’s 3G network.

Together, the 16GB iPad and MiFi cost $629.99. Purchased separately, the 16 GB iPad costs $499.99 and the MiFi costs $269.99 without a two-year contract.

Verizon is also offering three promotional MiFi data plans to its new iPad customers, $20 for 1GB per month, a $35 for 3GB per month and $50 for 5GB per month. Customers will pay $10 for each gigabyte of data use that exceeds the limits on their plan.

AT&T charges $14.99 per month for 250MB of data and $25 per month for 2GB of data. The month-to-month plans include access to AT&T’s Wi-Fi hot spots and don’t require a contract.

The launch of the iPad on Verizon’s network comes amid relentless speculation that Apple will break its exclusive iPhone agreement with AT&T and launch a CDMA-based iPhone with Verizon.

UBS equity analyst Maynard Um added more fuel to the rumor mill in a research note today, saying the “ability for Apple & Verizon Wireless to reach a working agreement on the iPad gives more credence to our view that a CDMA iPhone is likely to come.” UBS expects Verizon to launch the iPhone in the first quarter of 2011.

Apple has expanded its U.S. distribution of the iPad to Best Buy, Target and Walmart in addition to the carrier partners announced today. UBS expects Apple’s iPhone and iPad “should be two of the most heavily gifted items in addition to iPods during the holiday season.”