I upgraded from a 450 to 60D last summer, and haven't looked back!
Yes, glass quality is the overriding factor. Yes, the 60D will be updated sometime. Yes, the 60D doesn't have a Mg-Alloy and (totally) weather-sealed body. It was however a hugely satisfying upgrade.
The 60D's features which make the photography I desire achievable are worth the upgrade, and are something a glass-upgrade wouldn't have provided.
For me, the killer-features are the articulated screen, much-improved bracketing control, wireless-flash control, the top-mounted LCD screen, digital-level, far superior high-iso performance, higher-speed (FPS) even when shooting RAW, higher pixel-count (more confidence when cropping) and the Custom scene-mode (I just wish it had three rather than just one!). Even the (user-configurable) scene-modes are worthy of note.
Whilst I wholeheartedly agree that glass is the key to sharp shots, you need to get the shot first and the 60D's features are far superior to those of the 450D and go a long way to ensuring you get that shot in the first place.
Any camera will be updated at some time, and whilst the 60D's successor may be on the horizon it's by no means imminent. I'd say go for the upgrade and reap the rewards!