According to reports Nintendo are encouraging folks to tip them off about shops who sell the R4 flash cart. Nintendo has reportedly offered an anonymous reporting service.
<blockquote>Nintendo are offering a service whereby anonymous shoppers can tip off the manufacturer about shops that are offering the legally-iffy R4 Revolution device. The cartridge allows for 'data' (read: homebrew and, mostly, illegal ROMs of games) to be loaded from a Micro SD card onto a Nintendo DS. Tokyo's Akihabara and Osaka's Den Den Town are rife with people selling the products even today, despite many companies (including Nintendo) cracking down on its distribution.</blockquote>
News Source: <A href="http://news.spong.com/article/19445/The-Week-In-Japan-Wii-Dissing-R4-Snitching?via=rss" target="_blank">Spong</a>