iFaith, from what I'm reading, is only for Windows. The Mac people will have a tough time with this, myself included.
Could anyone explain to me why the developer would wait around until 5.1 to release this? Is he hoping that the JB will work on 5.1? If it doesn't, he loses a lot of potential people that won't be able to use his jailbreak with a tool like iFaith.
In my opinion, if he's got it working now, he should release it right now, I'm personally very OK with not upgrading to 5.1, as a matter of fact, I miss my OS4 with lock info and Pwntunes and safari downloader -- if I wasn't given a replacement phone with OS5 on it, I would have never upgraded, I don't see a single benefit of OS5 over 4.