I had surgery to "lengthen" one of the IT bands after years of trying physical therapy, massage therapy, expensive shoes and orthotics, cortisone shots and even acupuncture. None of it worked and as a last resort I tried this surgery. The surgery involved the removal of built up scar tissue and the addition of a small "v-notch" in the band itself, which I guess was supposed to allow the IT band to lengthen. It wasn't very invasive and was done microscopically. I would guess it was about 6-8 weeks before I could do any sort of running. Once building back up my mileage, I was okay for about two months and then ended up right back where I started with full-blown ITBS. So unfortunately, the surgery did not work for me.
I will tell you what did work for me, even though I'm sure to get skinned by all you crazy Let's Run posters. Going minimal. For years I ran with custom orthotics and in $140 shoes because I was told it was the only way to fix my injuries (which went way beyond ITBS). Then, after I had exhausted my options, I threw caution to the wind and started running barefoot. It fixed everything, I swear. It's probably because barefoot running is entirely a different experience than running shod, especially because your stride, foot strike and center of gravity are very different. In any case, while it was an adjustment, it worked wonders for me. Now all I run in are VFFs and occasionally, for marathons, xc flats. I'm not saying it's for everyone, but if you've tried everything else and it's failed, I suggest giving minimalism a try. Just be sure not to say you did on the Let's Run message boards. =)