CRJ200 Captain holding in position at ATL describes a jet blast incident which affected the preceding CRJ as it rotates. The jet blast was caused by a B777 perpendicular to the runway.

Narrative

When lining up on the runway one of my habit patterns is to check the windsock and watch the preceding aircraft's rotation observing how the winds affect it. Something didn't add up when I saw the preceding company RJ rotate because winds were light out of the west northwest (280 07 KT 230V300); but after rotation the preceding aircraft was abruptly displaced 15 to 20 FT to the north. There was then a brief discussion between the Controller and the pilot of the preceding aircraft regarding jet blast from a B777 that had apparently cleared to the south at Taxiway C stopped unexpectedly and then proceeded west on Taxiway E. The jet blast event occurred when he applied power to continue taxi. I did not observe the B777 stop and restart taxi but when the discussion was taking place I could see him westbound on E near C. The B777 crew stopped unexpectedly and the Controller still cleared the RJ for takeoff. This resulted in B777 jetblast after rotation. After observing this event I contacted the crew of the preceding aircraft and we discussed what happened. We all agreed that it would be helpful to file reports. It would be helpful if FAA publications discussing wake turbulence also included material on jet blast incidents such as this. This event was more intriguing than dangerous however; imagine if this had been a narrow and/or contaminated runway. In this case the PIC elected to continue; that seems like the best course of action to me but what is known of the ramifications of aborting in this scenario? Is there anything about ATC/Pilot procedures that could be improved to emphasize this hazard? Is the B777 with its massive engines a greater threat than other heavies such as the B747? This event caught me by surprise. I encourage you to inform others so they are more situational awareness.