If you visit the 3DS eShop, you’ll be greeted with a message stating that a new system update is available, which brings the Nintendo 3ds/3ds xl to the latest 8.0.0-18 J/E/U, it doesn’t appear to include anything of great importance, just minor improvements and adjustments,Below is the Nintendo's official description of the update: “System stability improvements and other adjustments Further improvements to overall system stability and other minor adjustments have been made to enhance the user experience.”
For 3ds flashcarts, you can upgrade your system to the latest version directly, coz no flashcarts were locked in this firmware update, if you are looking to buy the best 3ds flashcart for your 8.0 device, I'd recommend this r4i-sdhc 3ds rts card http://www.thegamerdepot.com/r4isdhc-3ds-rts-flashcart-for-3ds-xl3dsdsidslds-p-166.html you will be able to play almost all ds games, as well as homebrew games, and it has many real time functions (like cheat activation, save during the game, find your own cheats, you can read txt files and view pictures during the game and you can make the game slower).
Below are the list of confirmed to be working 3ds flashcards with the latest 8.0.0
R4i-sdhc 3ds rts
R4i gold 3ds rts
2014 R4isdhc dual core