Final Fantasy XIV's current open beta has been the lack of a hardware mouse. The currently implemented software mouse has certain issues, among them the fact that (like any software mouse) performance can vary wildly depending on your framerate within the game. Amidst all the clamoring of fans for an official fix, a fan looked into the code and realized that the game already has the support coded in... it's just not enabled.
The fan-written patch to address the issue notes up front that it's an entirely unsupported change, will be wiped out by each new patch to the beta (patches have been coming almost every day), and simply enables the existing code hidden within the game client. There's also no word from Square-Enix at this time as to how the company views this alteration, as it technically falls under the aegis of being a non-permitted modification to the client. Still, if you're in the Final Fantasy XIV open beta and have little hope Square will activate the code on its own, a fix is being made available.
[Thanks to Cliff and Amana for the tip!]