Not terribly startling, no. Anybody that has thought much about advanced text editor features probably has a good chance of thinking to integrate a calculator with a text editor, especially given that spreadsheets are the essentially same idea restricted to a grid. I expect it's been independently re-invented hundreds of times.
Having said that, I'll definitely be sharing a link to your software to all my Linux-user friends. The document-as-a-calculator concept is a fantastic. There's tremendous demand for it as well.
http://www.google.com/search?q=soulver+for+linux