well, if you think about it, colombians were pretty dominant on climbs in grand tours in the mid/late '80's (pre-EPO). then they all disappeared. there were a few here and there performing well (parra at the '05 giro, for instance), but mostly they were anonymous. if the sport really has cleaned up, or at least cleaned up enough to prevent the 7w/kg climbing performances (which it has), you could say that it would make a lot of sense to see a re-emergence of colombians doing well on climbs. i'm not saying that everyone born in colombia has the potential of lucho hererra, but the physiology that comes with living there certainly lends itself to producing good climbers.
not saying they're all clean/less dirty than everyone else, but it's hard not to notice the trend.