The term 'patched' is a bit confusing. It means that Nintendo is selling a new 'patched' sudoku version in DSi shop, which is no longer allowing to play homebrew. Basically that's making it useless to buy the game since you'll just need to replace it by the older 'unpatched' sudoku version.
You might still want to buy it for two reasons: It's tendencially more legal when buying the game. And, when buying it, the DSi shop is probably somewhere registering sudoku as installed title (so it will show up in system menu) (not sure on that, but I would assume that it won't show up if it isn't registered in the system menu .sav file, or in the wrap.bin file).
Btw. is Sudoku really the best choice? When starting it, it's hanging for about 1 second in a White screen, then it's hanging for another second in LicensedBy screen, and then it's coming up with an entirely useless TouchToStart screen, and thereafter, after touching, it's finally letting you to boot your homebrew stuff.
I think there are around 4-5 other exploitable games. Are any of them booting faster... or are they even worse, with more delays, or requiring you to navigate through some menues before booting homebrew?
Just went to dsiware (european) and there are only 2 more xploitable games available and those are Legends of Exidia (800 points) and Fieldrunners (500) so I'll stick with sudoku because I already have the 200 points it costs and i won't need to add anything. I hope the title downgrading thing will work and if it doesn't I'll buy one of those.