If Journal isn't in that list of 5 apps, you should be able to find it (again, assuming it is in fact installed) by pressing on that grey X and swiping up as if it were a pull tab. That's how you would normally access any apps for which you don't have a shortcut icon on the home screen.
(In the 2.2 beta, you double tap that x, but on 1.6, it was a press-hold-slideup motion.)
If you do that, you should see a complete grid of applications like this:
If there are so many apps that you need to scroll (and I think even with the default installation that's the case, you need to scroll) then scroll to the J's and verify whether there is or isn't an app listed there called Journal like this:
I can't say for sure that if it's not there, it's not installed. But I can say that if it was somehow removed from the Home screen's shortcut bar, this is where you'd find it. If you press and hold it, then the homescreen should appear and you should be able to move the icon back into a spot on the home screen.