Actually the current Android plan states
"Rate plan contains a 1GB data usage level. Once you reach your usage level your speeds will be reduced. See our Fair Use Policy for details."
The 45 dollar plan has no mention of this.
I've been flashing Froyo onto the Barnes and Noble Nook Color. I can tether it to my Droid 2 on Cricket however, I keep a laptop mounted in my vehicle all the time.