What's the modern way to schedule jobs running on a computer? Is there anything better than cron? Context is data warehousing extract-transform-load jobs. Not interested in anything proprietary.
Have you looked at launchd, the new all-purpose task control daemon? Don't be put off by the fact that it's from Apple--it's open source, licensed under the APSL, which I believe is GPL-compatible, if you care about that kind of thing. It seems to offer many of the features you want, including task scheduling, preemption control, etc.
http://developer.apple.com/documentation/Darwin/Reference/ManPages/man8/launchd.8.html
http://www.macgeekery.com/tips/all_about_launchd_items_and_how_to_make_one_yourself