One of the most common questions I field these days is what is the state of spatial in Apache Solr? As of today, I believe I have backported all the functionality that exists on trunk to the 3.x branch. For details on this, see the Solr wiki page on spatial search. I would encourage people who are interested in spatial search to try it out and report any issues to the mailing list. For those wondering what those version numbers mean, see Yonik’s talk from Lucene Revolution (for the lazy: 3.1 is roughly the equivalent of Solr 1.5, we just changed the version number to be in sync with Lucene and trunk is always the “next” version, in this case 4.0)
As for Lucene’s spatial support, it looks like some efforts are picking up to clean up the old stuff and replace it with a new, improved version.