An ongoing study of Bromeliaceae, by a group of cooperating scientists, has lead to proposed new reclassifications for subfamily Tillandsiodeae. Using DNA sequencing, in combination with morphological characteristics, they determine which species have common ancestors. The authors are proposing further taxonomic splits to a number of genera to form monophyletic classifications.
Herb Plever, Editor of Bromeliana, has done an excellent job explaining all these changes. For more in-depth (and scientific) explanation, see Herb Plever's original article here in Bromeliana newsletter.