This came in from Nature today:
http://www.nature.com/news/2008/0802....2008.549.html
A search is about to start for radio emissions from the explosion of primordial black holes. Evaporation of black holes suggests these small primodial black holes should evaporate to a point where they explode, but so far none have been observed.
A new theory suggests that if extra dimensions exist in a curled up state, the evaporating black holes will reach a size where they are stretched by the looped dimension before they explode and disappear into this extra dimension. In this case the explosion observable in our dimensions would be much smaller.
The search may also find radio signals from colliding neutron stars and supernovae as a by-product.
Al.