ACARS may indeed be a "messaging system" and not a FDR as several astute posts have pointed out, but there also exists the possibility that very similar message sequences have been seen by AF (or other carriers) before on other flights that obviously did not crash. Maybe AF (or other carriers) has seen a similar ACARS message sequence several times previous to AF 447 and knows what flight conditions produced that sequence. If this type of ACARS message sequence or partial sequence has indeed been seen in the past, I would suspect that those crews will be further debriefed to see what else can be learned. The CVR/FDR may never be recovered in this instance. Analysis of the debris/wreckage that can be recovered along with analysis of what could produce those ACARS messages may be all that there is to solve this tragedy.