Tried date faceting in Solr 4.2.1 and it is not returning correct values. It has been deprecated like the wiki says. Instead I tried range faceting and it works fine:
q=*:*&wt=json&rows=0&facet=true&facet.range=PRESENTDATE&facet.range.start=2011-12-01T00:00:00Z&facet.range.end=2012-06-01T23:59:59Z&facet.range.gap=%2B1MONTH