  We have examined the interfacial thermal conductance {\sigma}int of single
and multi-layer graphene samples prepared on fused SiO2 substrates by
mechanical exfoliation of graphite. By using an ultrafast optical pump pulse
and monitoring the transient reflectivity on the picosecond time scale, we
obtained an average {\sigma}int of 5,000 W/cm2K for the graphene-SiO2 system.
We observed significant variation in {\sigma}int between individual samples,
but found no systematic dependence on the thickness of the graphene layers.
