This announcement is probably in response to bASIC's announcement. It doesn't increase my confidence in BFL as if they were scamming it would also make sense to make this kind of announcement. Pictures of the actual products and working demos would be nice...
I don't have pics or working demos for you, but I can tell you why the jally is only doing 4.5gh/s while the single is getting 7.5gh/s per chip - they didn't want to add a power brick. This limits them to the 5 watts they can reasonably expect to pull from a USB port (either a 1000ma port or using a dual USB adapter with 500ma ports) Assuming they had 7.5 watts to work with I'd bet the jally could pull 7.5 GH/s but it would then require a power adapter.