The screen is now blue because the theme is Curve original and the previous default was Curve Multi-Color--that was the one with the little colored buttons that let you choose your color scheme. You can still do that in your profile as Sir Osis described the other day.
As for me, I am practicing with theme creation in a testforum I have created. I'm only interested in colors and a header and the smf wikis have one about creating a theme--based on this curve. Well I'd be interested in more, but it's not a big deal, so I'm only focusing on colors and a header...it would be nice to have links to the blog and main site or the main site/blog nav bar too, but no big deal I have 5 tiny adorables who are a big deal!