  I review the progress in research on Intracluster Planetary Nebulae (IPN).
Hundreds of IPN candidates have now been found in the Virgo and Fornax galaxy
clusters, and searches of two nearby galaxy groups have made. From the results
thus far, approximately 10 - 20% of all stars in Virgo and Fornax are in an
intracluster component, but there are few such stars in galaxy groups. From the
spatial distribution of IPN, it appears that the intracluster stars are
clustered, in agreement with tidal-stripping scenarios. In Virgo, the IPN have
a large line-of-sight depth, which implies that the bulk of intracluster stars
in this cluster derive from late-type galaxies and dwarfs. I also discuss other
important developments in IPN research such as the detection of intracluster H
II regions, a possible detection of IPN in the Coma Cluster, and future
observational and theoretical developments.
