In a car, driver and passengers talk to each other naturally during a drive.  On a bike or scooter, each rider is in a private cocoon of silence, even when riding in a convoy.  This doesn't need to be the case, and the use of lightweight hand-held walkie-talkies is a sensible way to enhance the social aspect of convoy riding.  Not only can route instructions, warnings or incident reports be shared, but general conversations and comments are also possible, and fun.  In large convoys, particularly, the use of radios is a great safety feature.
Should you decide to explore this option, you need to consider these important factors:

1. For perfect bike-to-bike radio you really need a "comms unit" – this is a multi-channel amplifier with built-in noise-cancelling circuitry to remove wind, engine, and road noise from all transmissions.  Comms units were developed specifically for motorcycles / scooters because they are such a noisy audio environment, and get worse the faster you go.  The two main brands of comms units retail at around AU$350 for a rider-only setup, or AU$450 for a rider-&-pillion setup, and you can plug in not only your UHF radio but also your mobile phone, FM radio, MP3 player, GPS... they are great!  There is also a US-made unit for around AU$240 that comes complete with pillion headset, but is available online only, and is designed for battery operation only ( not 'mains' powered from the bike ).
2. If you don't want to face the expense of a central "comms unit" to route all audio inputs and control noise-cancelling, and want ONLY bike-to-bike 2-way radio, you will need two pieces of hardware: the radio and the transmission gear ( microphone, earpiece, cords, etc. ).  But be aware that bike-to-bike without proper noise-cancelling will never be very crisp and clean.