I know a young man who had a 6 month lease on an apartment in Oregon. After the 6 months, the lease became 'month to month' unless he chose to sign another agreement. He chose not to sign another agreement because he had met a gal he knew he would be living with. He went to the office to notify the manager that he was giving his 30 day notice. After the 30 days, he went to let the manager know that he'd be moving out that weekend, she notified him that he hadn't 'signed' their 30 day notice form and that he owed another full months rent before she would release him from his lease. My question: Why didn't she tell him, when he originally notified her of his intention to move, that she needed something in writing? How legal is it, for the manager to make him pay another month of rent, even though he's already obligated himself financially at his new location, after having the initial conversation with her about his intention to move in 30 days?

Ethical, no! Legal, yes! Ignorance of the law is no excuse. Your friend was required by law (and I suspect) the terms of the lease to give written notice that he was not renewing the lease. But, even if he had given notice you stated; "After the 30 days, he went to let the manager know that he'd be moving out that weekend". So, since he did not move BEFORE the 30 day deadline, the notice was void and the lease was automatically extended for another month.

Your friend owes the extra month because he violated the lease.

Even though the lease ended, the month to month was under the terms of the lease, so they were obligated to do exactly what the lease required.