Frame is great, wheels are great, and Ultegra 9-speed is a solid group; all that stuff will last a long time and serve you well. I'd keep all that.
The fork looks like a 1" threaded fork with a plug for a threadless stem, which is not particularly light, and not particularly well matched aesthetically to the frame, in my opinion, even though the fork is original.
There are 1" threadless forks with carbon steerers that will be lighter and nicer riding. Columbus Minimal is available new for about $250 and is a great fork. If you hunt eBay, you might find a Reynolds Ouzo in 1" or an Easton EC90 in 1", but they're rare and expensive.
If you upgrade the fork, you'll need a threadless headset. Say $100 for a nice shiny King headset.
Upgrading the handlebars to a shallow drop would make the bike look more modern and probably feel better. And while you're at it, you could get a better stem -- that looks like a chunk of black metal that came out of the Nashbar drawer.
Then I'd get a carbon seatpost and replace the pedals, which are two little boat anchors. You could probably take a half a pound off the bike by swapping out lighter pedals.
So, here's the bill:
fork 250
headset 100
handlebars 75
stem 25
seatpost 75
pedals 125
bar tape 20
Total 650, bike will probably be 2 pounds lighter or so.