  Weak gravitational lensing is a powerful probe of cosmology and has emerged
as a key probe for the Dark Universe. Up till now this science has been
conducted mainly at optical wavelengths. Current upgraded and future radio
facilities will provide greatly improved data that will allow lensing
measurements to be made at these longer wavelengths. In this proceedings I show
how the larger facilities such as the SKA can produce game changing
cosmological measurements even compared to future optical telescopes. I will
also discuss how radio surveys can also provide unique ways in which some of
the most problematic systematic errors can be mitigated through the extra
information that can be provided in the form of polarisation and rotational
velocity measurements. I will also demonstrate the advantages to having
overlapping optical and radio weak lensing surveys and how their
cross-correlation leads to a cleaner extraction of the cosmological
information. Key to the realisation of the great promise of radio weak lensing
is the suitable measurements of galaxy shapes in the radio data, either from
images or from the visibility data. I shall end with a description of the key
issues related to this matter and the radioGREAT challenge which has been
proposed to address them.
