Dunno about porting that, but I made a Cocoa wrapper app for tailing files. Still, using a terminal window is much easier.
Since this trick is new to me, I'll post it here. You can use the -n command to tell tail where to start dumping the file. An argument of +1 means start on the first line, so the command
Code:
% [b]tail -f -n +1 /var/log/mail.log[/b]
would dump the whole mail.log file and then proceed to wait for updates to also display.
-Rob