The Rupee symbol (₹), designed by D Udaya Kumar, got publicly announced on 15 July 2010. However, I'm yet to see it on many posts, blogs, comments, published pages.
It is however, available by default on Windows 8. So what if you're stuck on Windows 7? Well, here's a solution.
Microsoft released a patch to allow use of the ₹ symbol by pressing Ctrl+Shift+4. Here are the downloads.
For Windows 7 64 bit. Download Here
For Windows 7 32 bit. Download Here
Once you've installed the language patches, you simply need to do the following.
Now this should allow you to finally use the Rupee symbol across Windows. Enjoy.