It's been a busy week so far in Portland's startup community. Yesterday, Jive Software CEO Dave Hersh announced that he was stepping down after nearly a decade on the job. And today word comes that Portland-based Monsoon has been sold to Alibris, which competes against Amazon.com in the used book space.

Monsoon helps merchants sell books, DVDs, CDs, games and other products on the online marketplaces of Amazon.com, Buy.com, eBay and others.That's also an area where Seattle-based Mercent -- backed with $14 million from Madrona Venture Group and others -- is active. [Post updated with comments from Eric Best of Mercent]

Founded in 2002, the company said that it enables several hundred million dollars worth of transactions each year.

Mike Rogoway of The Oregonian reports that Monsoon employs 50 people in Portland, with all of those workers slated to stay on. Terms of the deal were not released, but Monsoon CEO Kanth Gopalpur tells Rogoway that investors got a good return on their investment of about $2 million.

The Amazon Strategies blog ponders the acquisition, with Scot Wingo wondering if Monsoon will continue to support Amazon and whether Amazon will continue access to their marketplace.

Gopalpur indirectly addressed those concerns in today's press release. “This transaction will provide the combined Monsoon-Alibris customer base with even more opportunities to expand their businesses and increase sales," he said. "We will be able to take advantage of additional resources, technology, and capital in order to deliver more and better solutions to grow our customers’ businesses on all online marketplaces.”

UPDATE: I asked Eric Best of Mercent of his take on the deal. Here's what he said:

Mercent provides some overlapping services, but with a focus on a different market. Like Monsoon, we’re generating consumer demand for our retail clients’ products through Amazon and eBay among other online shopping channels. But Mercent is focused on optimizing online product advertising for the world’s largest retail brands.

Unlike Monsoon, we don’t serve small or used/discount product sellers, and we don’t provide the basic ecommerce functionality like inventory management, order management, point-of-sale, online storefront, or shopping cart services offered by Monsoon -- as we assume our clients already have this infrastructure in place.

Alibris is looking to increase its value proposition to its portfolio of 15,000 3rd party sellers of new and used inventory by offering up Monsoon’s services. This sounds like a logical extension of the marketplace services they’re already providing to these sellers. I expect we’ll see further convergence of established e-commerce platforms and even retailers with complementary online advertising companies as the line between these two market spaces continues to blur.