Membrane proteins are hard to get to. They've got super hydrophobic regions for stuffing inside membranes, they've often got multiple glycan domains and they can have annoying 3D structures that are just clumpy (best term I've got this morning). Even the most comprehensive global proteomics studies we've ever seen appear to under-represent membrane proteins. (Post I wrote on that last topic last year).
This group essentially enriches for hydrophobic peptides by throwing in a high organic separation that results in a downstream loss of the most hydrophilic peptides. EDIT: Loss isn't the correct word. Let's go with "enrichment of hydrophobic peptides in relation to the general peptide population."
The RAW files are up at PeptideAtlas here and it's striking how much signal they get in the high organic section of their chromatogram through this process.
It's fair, I think, to mention that this approach isn't entirely new....
...but the changes are definitely novel enough to warrant checking out this iteration if you're looking at membrane proteins!