Well. Microsoft actually "commended" the jailbreakers and did not guarantee that future patches would leave it open; that is, they didn't whole-heartedly condemn it. Check the news from back then, 'tis true. I don't know if the jailbreak is compatible with 8.1 (XDA would know).
The so-called "jailbreak" is a "soft" method, meaning it doesn't mess with firmware or anything that automatically negates the warranty of your device, the way cellphone jailbreaks work. In fact, every time you reboot, the Surface RT jailbreak is erased without a trace, and you must run it again to side-load the applications you want. Naturally, this jailbreak won't allow you to install any ol' legacy Windows software, only ARM-recompiled ones. I use mostly PuTTY (secure shell, telnet, SFTP) and sometimes Audacity as my sideloaded applications, but because I don't use them that often, my RT remains in a pristine unjailbroken state...until I run the break again.
At this time, I don't know what audio editing apps are available in the store since it's been over half a year since the OP's question.
Editing for posterity: The jailbreak no longer works in Windows 8.1.