Store and query numeric intervals in Lucene (Greplin open source)

Please excuse my ignorance, but can someone tell me why this is being voted up so quickly?<p>Lucene already has range queries, is this just enumerating all of the values within a range for the fields? It looks like they don't index these values either in the examples.<p>Edit: Not that this should take away from adding to Lucene, for that I thank you :)

One application that this might be useful for is an IP lookup. Typically they're stored in block ranges and querying can be tricky, especially if its an offline operation done with hadoop. Could also be counter-productive, but an interesting thought.