Sprint Nextel has announced the launch of its next-generation mobile WiMax broadband service, known as XOHM, in Baltimore, Maryland. Unlike traditional 3G cellular data products, Sprint will offer its 4G service to subscribers on a month-to-month, no contract basis; in fact, at launch, even day passes are available, albeit for a relatively pricey $10. Besides the day pass, $25/month home and $30/month on-the-go plans are offered, as well as a so-called "Pick 2 for Life" option which covers a pair of devices for $50, for the length of membership. The company is promising 2Mbps to 4Mbps downstream speeds -- twice to over four times as fast as real-world EV-DO and HSDPA connections -- for supported devices, which at launch include a $60 Samsung-built ExpressCard modem and $80 ZyXEL-manufactured home modem (a USB-compatible version is scheduled for later in the year).  Along with its newly-acquired subsidiary Clearwire -- soon to be a WiMax MVNO -- Sprint expects to expand its nascent network to gradually cover the full US, with Chicago and Washington, D.C. getting switched on next.