I have Console monitoring some log files, but found it wasn't always scrolling the log window automatically to display the latest entry.
It's not obvious, but down the bottom right of the log windows are some controls for Earlier/Later/Now. The Now button is actually a toggle; if you click it until it highlights in blue, the log window will always automatically scroll to the latest entry.
[crarko adds: I can confirm this in Console.app in Mountain Lion, and that there is no 'Now' button in Snow Leopard. Probably it's also in Lion, but perhaps someone can check and confirm that for us.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=2013010813261752