Senlis on 06 January 2010
http://www.neowin.net/news/main/09/11/12/microsoft-bans-1-million-xbox-live-accounts
According to this article, it seems that modding your console is not illegal in itself. However, it violates the usage agreement (in the case of Microsoft) and can have negative repercussions from the manufacturer. I am guessing that other manufacturers have similar clauses in their usage agreement; It will surely void your warranty.
