Stored procedures are available as capabilities CALLABLE from the Cypher language since version 3.0
- A first reference can be found here https://dzone.com/articles/neo4j-30-stored-procedures
- A remarkable example, showing how graph can be processed in the large through procedure to achieve network clustering and community decetion, here http://www.markhneedham.com/blog/2016/02/28/neo4j-a-procedure-for-the-slm-clustering-algorithm/
EDIT
As Neo4J 3.0 has been released in April'16, the stored procedure became an official, Apache 2.0 licensed, repository.
Available procedures range from data manipulation/import to Spatial and complex graph algorithms (es. Page Rank, Dijkstra, Community detection, betweenness centrality , closeness centrality, etc)