If you don't use it then you have nothing to worry about
It's a program for improving the transparency effects in Vista

You can find more information on the program at http://www.codegazer.com/vistaglazz/
Basically it lets you have two things:
1. You can change the default visual style in Vista to have transparency on maximized Windows instead of just normal Windows only.
2. You can use non-Microsoft visual styles in Vista.

It shouldn't be too long though before a new version comes out that supports SP1.
Also the only reason SP1 messes with Vista Glazz is because Vista Glazz edits system files to do what it does.
All normal programs that don't edit system files should function just fine after SP1 is installed.

@whs,I saw a post earlier about sp1 creating problems (goofing it up)with Vistaglazz.And no,I haven't downloaded sp1,my machine is just fine. I installed the "crap cleaner" CCleaner,and it made my machine faster, if anything,a good freeware for sure.I'd like to thank jd for the info on VistaGlazz.You guys are ok,thank you.