eBay’s PayPal online payment service has taken an aggressive stance this week with deals signed by Southwest Airlines, Northwest Airlines, UATP, Devix, CardinalCommerce, and Alienware. PayPal also unveiled its “Mobile Checkout” service and the opening of PayPal Data Services in Austin, Texas. Dallas-based Southwest Airlines, which currently serves 63 cities in 32 states, announced that its fares can now be purchased online using PayPal. Last month PayPal signed Northwest Airlines to accept PayPal, its first airline client. Washington, DC-based UATP, which serves 220 airlines, has launched the PayPal option. NJ-based Devix has been certified by PayPal to integrate “PayPal Express Checkout” into the latest Devix offering for e-tailers. OH-based CardinalCommerce announced partnerships with SkyMall, DVD Empire and DVD Planet and via the “Cardinal MAX” platform has created hosted mobile shopping sites that are fully integrated with “PayPal Mobile Checkout.” FL-based Alienware added the PayPal option to its “Titanium Account.” PayPal formally this week announced the launch of “Mobile Checkout,” a service allowing consumers in the U.S., U.K. and Canada to buy using the mobile Web. PayPal also announced that PayPal Data Services, Inc. is opening a new technology development center in Austin, Texas and plans to hire hundreds of local technical professionals in the next three years. PayPal has more than 143 million accounts in 190 markets and processes 17 currencies worldwide.