The new Samsung 830 SSD's - with the 6GBps controllers - are significantly quicker.
I just ran a BlackMagic test a second ago since my old 2011 MBA is sitting here besides me.
The MBA 2011 128GB (Samsung) ran about 250 both ways.
The MBA 2012 256GB (Samsung) ran about 400W, 450R.
I've heard there can be some disparity based on the nature of the test and how Toshibas and Samsungs handle compressible data differently however the difference is not insignificant and, from an anecdotal standpoint, it certainly feels a LOT snappier.