Many companies don't do marketing for numerous reasons (budget being the primary reason). However, they do hire salespeople - to close sales, bring in revenue. That's the job of sales - close deals. Marketing's job is to develop qualified leads, generate interest in the product, and more.
Recently, my consulting business has seen an increase in interest in Product Marketing, especially for Hosted PBX. Here's what Gartner says about Product Marketing: "Product marketing is responsible for messaging and positioning, segmentation, competitive intelligence, launches, deal support and many other critical functions."
The Gartner post continues with marketing's role in "Making Sales Enablement More Robust". I did a fair amount of channel sales enablement last year on projects. "Considerable time and effort needs to be put in to ensure that sales can truly add value to their interactions with prospects." The Value Statement, case studies, customer stories, positioning, and competitive analysis are all ways that marketing can add value to the sales process -- or at least provide knowledge to the salesperson to use in sales calls (that are increasingly becoming on-the-spot interviews).
The noise in the market combined with all of the information on the Internet at any buyer's fingertips 24/7 means that sales has changed. Have you?