Hmm, mobile 4G from Clear is around $45/month. Google Voice offers a phone number with voicemail, SMS, and a multitude of other features.
Wouldn't it be nice if someone were to write a device driver for Android to use the 4G modem from Clear? $45 / month for unlimited data, voice, and text messaging plus you would use the same 4G modem at home in your PC. They are offerring data rates of 2Mbps to 6Mbps with Clear.
I suppose someone would also need to write custom software to get Google Voice to use the built in mic & speaker on the Nexus One.