Does anybody know of a similar device that includes Homeplug?
No, unfortunately. There also aren't any plug computers that can run off POE (Power Over Ethernet).
Being small and cheap is a key part of plug computers appeal. There are many technologies that would go well with a plug (e.g. WiFi, Homeplug, POE, USB, ESATA, RS232, RS422, I2C, etc.), but including them all would be size/cost prohibitive. The manufacturers have to make a judgment call about where the "sweet spot" lies. The result is often a "one size fits nobody" situation, where the plug is 90% right for your application, but the missing 10% is a deal killer. Building a custom plug is impractical at low volumes.
P.S. I bought a Shevaplug last year. I had no idea what I'd do with it, but it sounded cool. Honestly, I still don't know what to do with it. Luckily I can afford to blow ~$100.