Barit & others,
Unfortunately even the RAAS GPWS add-on may not have prevented this tragedy. It uses GPS as its position source so while it works well when you're (say) entering an active runway or at a threshold I'm not so sure about how well it can discriminate between two intersecting runways. I don't remember any "Intersection" calls when it was demo'd at last year's SAE GA Conference but Honeywell - the old Sundstrand group in Bellvue, Washington - are always upgrading the product.
Another aspect is that most RJs do rolling takeoffs so even with a heading input from the AHRS,by the time the platform has settled on the runway heading it could be too late to prevent a runoff accident even if you don't get airborne. Quite a few of the later Proline 21-equipped biz-jets have IFIS which can display the current aircraft position on the airport chart IF it is a "geo-referenced" one but again, by the time a crew realizes the mistake it might be too late.