YES!
The 10.5.3 update to OSX finally fixes the problem where the Aperture Library would get backed up from scratch multiple times.
In previous versions of OSX, if you had Aperture open while a backup started, Time Machine would skip the Aperture Library until you closed Aperture. Then, the next backup would do a complete copy [...]

About the Mac OS X 10.5.3 Update:
Addresses compatibility issues with Aperture 2.
If it indeed fixes the problem where Time Machine would do a complete backup of your Aperture Library if you had Aperture open the last time Time Machine backed-up your system, then I’d be happy… this was really a pain… too bad Apple isn’t [...]

As Apple states in the update’s KBase page:
About the Mac OS X 10.5.3 Update:
Includes additional RAW image support for several cameras.
Well, it would be nice to know which ones.
[UPDATE]
Well, hot on the heels of the 10.5.3 update, here’s the Digital Camera RAW Compatibility Update 2.1 that brings RAW support for the following cameras:

Canon EOS Digital [...]

So,
I was going back to some of my pictures I imported using Aperture 1.x and, since I’m using Aperture 2 now, I wanted to try the 2.0 RAW developer on some “old” pictures.
See, I didn’t convert my whole photo library from RAW 1.1 to RAW 2.0, because I noticed it tends to change the color [...]

So, Apple really DOES listen to its pro users, and has just released Aperture 2.1, a mere 6 weeks after 2.0 and two weeks after 2.0.1.
Let’s see what the 48MB update does for you:
[UPDATE: I noticed something: on my MacBook Pro, Aperture 2.1 now launches in like a couple dock bounces, it's almost instantaneous!]
[UPDATE 2: [...]

According to this tech note from Apple’s KB,
Time Machine may back up the entire Aperture Library on each run:
This can happen if the Aperture library is included in Time Machine backups and a backup occurs while Aperture is running. In this situtation, Time Machine excludes the Aperture library from a backup while the application [...]

Aperture 2.0: the Ars Technica review:
Aperture 2 isn’t doing anything groundbreaking over the previous version, but the better overall speed and Quick Preview combined with background processing alone will be worth the cost of the upgrade for many users. If you’re just checking out Aperture since running like the wind from version 1.0, rest assured [...]

So, according to this tech note on Apple’s knowledgebase, you can now safely use Time Machine to back up your Aperture Library (before the OSX 10.5.2 update, it was recommended to exclude the Library from the Time Machine backups for fear of giant asteroids destroying your house or something.
I just upgraded my laptop to Leopard [...]