I've been using Notepad++ for UnrealScript editing for some time now, and of course created my own user-defined language to highlight UScript. Here's what it looks like:

I think it should contain every single keyword in UScript, plus it also highlights all the structs and consts declared in Object.uc (vector, rotator etc) and Actor.uc, since they are used a lot. The colour scheme is similar to the one for the script editor that came with older versions of UEd.
It's not quite perfect e.g. it doesn't highlight hexadecimal numbers fully, and will only highlight the * and / operators if they have spaces on both sides, but I think it's probably as good as Npp will allow. Oh, and you might need to turn off current line highlighting (Settings->Preferences->Editing->Enable current line highlighting), because it doesn't work well with negative colour schemes like this.
You can download it from Notepad++'s wiki. Use it, and it will make your code more awesome!
EDIT: I have written an autocompletion file now too, available at the above link along with the syntax highlighting file. This file had to be created manually, so I only added everything in Object.uc and Actor.uc, and it will have to be updated manually if those change in future UDK releases, but it covers a lot of useful stuff - no more struggling to remember in which order the arguments for Trace go!

I think it should contain every single keyword in UScript, plus it also highlights all the structs and consts declared in Object.uc (vector, rotator etc) and Actor.uc, since they are used a lot. The colour scheme is similar to the one for the script editor that came with older versions of UEd.
It's not quite perfect e.g. it doesn't highlight hexadecimal numbers fully, and will only highlight the * and / operators if they have spaces on both sides, but I think it's probably as good as Npp will allow. Oh, and you might need to turn off current line highlighting (Settings->Preferences->Editing->Enable current line highlighting), because it doesn't work well with negative colour schemes like this.
You can download it from Notepad++'s wiki. Use it, and it will make your code more awesome!

EDIT: I have written an autocompletion file now too, available at the above link along with the syntax highlighting file. This file had to be created manually, so I only added everything in Object.uc and Actor.uc, and it will have to be updated manually if those change in future UDK releases, but it covers a lot of useful stuff - no more struggling to remember in which order the arguments for Trace go!
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