Soon after registering Delicious Library it stopped working with a
Beta 4 Expirederror. Mailing the support address on the website got me a email back, one minute and eleven seconds later in fact, from Mike Matas telling me that they'd "forgot to pull the expiration stuff out of [the] final release" and promising that it'd be fixed soon. Twenty minutes later I got another email saying that it was fixed and that a new disk image was available on the website.
You can't really argue with that level of support.