Halo 4 to receive a public beta, 343 Industries announced in a Q&A with franchise development director Frank O' Connor. He answered a slew of fan questions about Halo 4, revealing that it would be possible to play Grifball, that there would not be a color-blind mode (though considerations for that audience have been made in art decisions), and a few other tidbits. Check out the full factsheet here.
In related Halo 4 news, Microsoft recently won a legal battle against the bogus website Halo4beta.net, but as there won't be a Halo 4 beta we don't expect it to be put back into official use any time soon. Microsoft has also filed a complaint against Halo4beta.biz.