Hearing aids are electronic, battery-operated sensing devices which aim at compensating various kinds of hearing impairments by means of appropriate signal processing. Most of today's hearing aid systems consist of two appliances working independently of each other. However, collaboration using a wireless communication link would allow to improve the overall beamforming capability of the system, hence providing better rejection of interfering signals. In this paper, the problem is considered from an information-theoretic viewpoint. We provide the necessary theoretical background to precisely quantify the gain achieved by collaboration as a function of the communication bit-rate. The beamforming capability is then discussed for the setup considered in this work.