I have no idea of what Amazon's policy is regarding this. I suspect that it depends upon what you are going to do with the info! I have quite a number of gizmo's that log on and "scrape info" from sites, but I don't use or distribute this info in anyway that violates user agreements. Basically if I just automate something that I could do myself manually and use the info like I would if I did it manually by cut-n-paste (subject to user account agreement), normally this is ok.

Update: legal things aside, I have "throttles" on my web-automation stuff. I don't want to be impolite by generating too many requests/time. My programs can be patient. How much load you are generating on the host side should be a consideration for your web-automation stuff, or at least it is for mine.