Yeah, this came up the first time we wrote about OAM [0]. There's a pretty informative (and heated) discussion about it in the comment thread -- Bo Thide defending his work from attacks made by other scientists.
Call me naive, but the comments of Bo Thide in that link have a very inconsistent level. One comment he sounds like a physics professor, another one like a dude that just read "Maxwell's equation for dummies", making leaky analogies between OAM EM waves and spin-stabilized gun projectiles. I guess the analogies are a habit of teaching.
[0] http://www.extremetech.com/extreme/120803-vortex-radio-waves...