Dell already offers a/g option from Broadcom: Broadcom keeps pushing at the enterprise, and today announced they are shipping their mini-PCI 802.11a and 802.11g adapter, which, by g's nature, includes full 802.11b support. (Broadcom's chipset has been certified as full Wi-Fi for 802.11b as of a few weeks ago.)
Dell is the first of what Broadcom hopes are several manufacturers that will offer their adapter as an option, especially attractive to the enterprise. Intel won't have an a/b or a/g option until the second half of this year, by which time laptop manfacturers may be entrenched in their current option.
Broadcom pointed out to me that Dell revises its business laptops only rarely; the last time the Latitude line was revised was in 1997. Dell likes to offer a predictable product that a company can commit to as a stable, identical platform for an extended period of time in large numbers of units.
Broadcom noted that it provides a single driver to support b, g, and a/g, meaning that a single disk image for installing the operating system on a laptop can be used for whatever Broadcom adapter is included.
All of this points to Intel having a more uphill battle for wireless supremacy than predicted last year, although all the laptop makers offering Broadcom adapters also offer Intel's as a default, no-cost option. It's just that Intel's adapter isn't necessarily what the enterprise wants today.