Nintendo has rolled out a new firmware revision for their latest incarnation of their line of Nintendo DS portable video gaming consoles. It seems v1.5 of their firmware blocks flashcards again which means you can either turn on off the Wifi or wait for a fix. Not is much known about other enhancements other then the anti-flashcard fix.
"Yes, we are the first evidence of the release of a new firmware for the DSi (1.5) which seems to block all the flashcards are currently for sale: waiting for updates from our entire staff's advice is to not upgrade and wait to be understood whether and how to get around the obstacle and continue to use the latest Nintendo handheld with flashcards in our possession."