Hells yeah! If you've pre-ordered an import already, and payed top dollar for shippin', you could be tossing red shells by Friday!
After a couple searches to some regular import stores today, I noticed some stores will have Mario Kart Advance in stock as early as tomorrow!
Mario Kart Advance is set to release in Japan on Saturday, but it looks like distributors have been sending them out early. If you're dying to get your hands on Mario Kart for your GBA, you can pick up the import game for around 45-50 bucks (without shipping).