Windows, Mac OS X, Linux
Almost every piece of hardware has some form of software running on it. Whether it's microprocessor firmware or FPGA RTL, developers from other teams must be involved early in the design cycle and have easy access to the project afterwards to reference pinouts and design details.
However, it's typical that firmware and FPGA engineers lack access to the often complicated and daunting PCB design tool. As a result, collaboration is performed away from the actual board design, using email, PDF attachments, and a large CC list in an attempt to keep everyone in the loop. This method has no inherent version control and multiple files are distributed over time, leading to confusion as to what version to look at. Even with a separate version control system, other engineers are stuck installing a local copy of the CAD tool or a viewer just to open the files. The output from design discussions, group decision making, and schematic/layout reviews are often isolated in multiple email threads; they are not captured in a central place for the team to reference.
Since Upverter runs completely in your browser, it's simple to add other engineers to the project or to share the design with a private URL. There's nothing for them to install, the design is always available from anywhere, and they're always looking at the version you want them to work off of. Upverter's interface is simple and intuitive -- navigating through Upverter is as easy as panning around Google Maps. It's also easy to link your Github project to your Upverter design.
Upverter's markup tools allow other engineers to directly annotate the design and contribute to a central, comprehensive list of Issues. Each Issue contains an independent discussion thread so the decision-making between hardware and software engineers is captured for the whole team to reference. Since all engineers markup the same, central design, they are able to both add their thoughts to, and be inspired by, comments left by teammates. Software engineers can assign Issues to specific hardware engineers, giving confidence that nothing will fall through the cracks.