The last time this was posted on HN, I did a quick writeup on my understanding of it (reposted here):
"For the curious, this is an optional program at SourceForge being offered to developers as a way to monetize their work. The developer needs to specifically request it. SourceForge gets a cut, so does the developer. The installer is their first stab at this process and is using the bundling technology from Ask.com. As offer-based installers go, this one is about as good as it gets. It makes a single offer and has an Accept and Decline button with the user selecting whichever one they want (not a pre-checked box accepting the offer above a Next/Continue button). If accepted, the installer installs the offered software and it gets a standard entry in Windows' Add/Remove Programs that works as expected. If declined, the installer continues. The installer then downloads the originally-requested software.
The two issues with the current installer are that (1) it is served in place of the requested file with no indication that a substitution is made as the user downloads and (2) it requests admin rights before it starts downloading the software, which can be a security issue. Roberto (who posted the article) has stated that they are working on #1 in terms of the text shown on SourceForge as you select to download and download. As for #2, there may be some ways to rework the installer so this is not an issue. I'll mention it to him when I speak to him.
SourceForge has one other revenue-share program with developers where you place the SourceForge-branded download buttons on your own website that link to your downloads on SourceForge and you get a small cut of the ad revenue made from the download page.
If I recall correctly, SourceForge has been losing money for a few years now. Dice Holdings picked up SourceForge and Slashdot while Geek.com kept ThinkGeek.com, so they are now separate entities. These new experiments are attempts to get SourceForge to be self-sustaining/profitable. Ad revenue alone likely won't cut it.
Unfortunately, Google Code, Github and others don't offer the full breadth of services that SourceForge does for open source projects. Google Code, Github, and others have all ditched binary downloads, so SourceForge is one of the only providers to make binary downloads available to Windows and Mac user at no charge. This is why SourceForge is popular for real apps (FileZilla, Pidgin, PortableApps.com, etc) and Github is popular for components (node.js, jquery, rails, etc). The code zips available at other providers are of no use to end users.
As full disclosure, I run PortableApps.com, one of SourceForge's largest projects pushing quite a few TBs of downloads through their mirror network. We make use of the SF-branded download buttons revenue share program but do not make use of nor have any plans to use the "enhanced" installers. Everything I've discussed here is already publicly available, I just thought it would be handy to have in one place."
After that post, it was pointed out to me that Github has added in the ability to host binaries, but I would wager they wouldn't take kindly to the kind of bandwidth that the major SF projects like PortableApps.com push through. I've also been in touch with Roberto who made the mentioned post on SourceForge about some suggestions and options including doing an open source installer that the end-user/sysadmin can verify before installing instead of it being a downloader installer with the offer built in but not the app you want.