Last but not least, there is now a _watchdog() hook that modules can
tap into. In other words, it's now possible to integrate with
existing logging applications or to write custom logging handlers
(i.e. to send you an SMS message when something goes wrong, or to
send you a Jabber notification when someone posts a new comment on
your Drupal blog).

If you're a developer, you'll notice that we now have additional
"watchdog levels" like WATCHDOG_CRITICAL and WATCHDOG_DEBUG. These
are conform RFC 3164 and are defined as constants in bootstrap.inc.
Check 'em out.

To module developers:

Please be careful about being too generous with the highest severity levels,
such as Emergency, Critical, and Alert. Use sparingly and only when needed
so as not to clutter things (no one wants php undefined variable notices
sent to their pager!)

Also a new project has been created for logging and alerts. It has the emaillog
alert module, compatible with HEAD (no nightly builds, because there is
no 6 tag yet, but get it through CVS or the Browse CVS link.

http://drupal.org/project/logging_alerts

This is a good demo on how to use the new hook too. The email message
is themable.

The patch is a little rough around the edges -- most notably on the
documentation side (help texts, form descriptions, terminology) ...
We'll want to work on that, and I expect to see a number of small
follow-up patches to polish some of this.

It would be nice to get feedback from the doc team on this too (sepeck,
laura)? See patch below.

We'll also want to provide some basic instructions on how to setup
the syslog routing in syslog.conf.

There is a URL linked to in syslog settings to the syslog.conf man page
I expanded that a bit, and added more instructions.

We'll want to formulate practical
advice as when to use dblog and when to use syslog. Feel free to
help with that, as you explore the new functionality. It can be done
in multiple small steps. :-)