We've got a whole pile of projects that have been started or near completion: IPv6, separating the GUI and ping engine, MAC OSX version, server groups, hosted "cloud" PingPlotter, updated web interface, etc. Definitely not being abandoned - just not moving forward as fast as any of us hope.
We're hoping to have a new version (probably beta, because it has a new MSI-based installer that hasn't had a very diverse test base yet) out in the next week or so. You can reset the beta warning by "touching" the file date on the PingPlotter.exe file you currently have - you can either download a utility to change the date/time of a file, or you can do it manually via a command prompt like this (change to your install path first): "type "PingPlotter.exe" > c:\TempDir\PingPlotter.exe" - then copy your new PingPlotter.exe to the original directory. That will change your file date to now and reset the warning. The easiest way might just be to wait a week or so, though, and we'll get you a new build.
Sorry for the inconvenience - and thanks for checking in.