Update: While Dell's announcement is a welcomed one - not to mention requested for so many years - how actual prices of software-less PCs turn up in the short and long term remain to be seen. With this I mean that you won't necessarily save money because of this. While the OS does usually come at a cost to the manufacturer (and hence the consumer), Dell and many other OEMs get some of that money back from trial bundles and other crappy stuff you get in your HDD when you buy a new PC. In fact we can already see reactions and price comparisons that "don't make sense," but you have your answer already.
As a result of Dell's IdeaStorm, in which they have been soliciting numerous suggestions from their customers, Dell will now allow the purchase of notebooks without Windows. Staring with the Latitude series, they will join various desktop models sold by Dell in their n-Series, hardware without coupled software.
This isn't as far as including pre-installed Linux or any other bundled software, but does give customers more freedom in configuring a PC purchased from Dell. The IdeaStorm of course remains up, and it is encouraging to see a company reaching out to their customer base and reacting to their demands, rather than remaining stuck in the dirt.