Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_2_6 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8E200 Safari/6533.18.5)
Verizon does split messages, but it's been stringing them back together on the phone for me. Perhaps this is because it is two iPhones both on Verizon. Are your lengthy messages coming from another carrier?