GeoWave is an open source set of software that:

- Adds multi-dimensional indexing capability to Apache Accumulo

- Adds support for geographic objects and geospatial operators to Apache Accumulo

- Contains a GeoServer plugin to allow geospatial data in Accumulo to be shared and visualized via OGC standard services

- Provides Map-Reduce input and output formats for distributed processing and analysis of geospatial data

Basically, GeoWave attempts to do for Accumulo as PostGIS does for PostgreSQL.