Hello smortaz,
Your post reminded me DataNitro[1] (previously IronSpread), a python-in-excel solution that was featured on HN nearly a year ago[2], and a YCombinator-backed company.
As far as I'm aware it seems closed-source and costly, while your solution is open-source and free. But how does it compare functionality-wise?
At my company we're using using Excel pretty often and python is growing, so using such a tool could be a really convenient.