wondering seems like ...why not?
Don't believe anyone you see here, if you do, then you're gullible... You can play 3DS games on a DSi & DSiXL. and its all on the sticky....
1st you need to file down the nub on your 3DS card to fit in your DSi.
Next you need to set your internal clock to 2000, you don't really need to, but it helps speed things up.
Anyways stick your 3DS game in and power on the unit. Then power it up and download any DSiWare title, free or not.
You'll need to power on, boot that game/app, and poweroff 2000 times, and the glitch on the DSi will allow you to play 3DS games.
If you have your clock set to year 2012, you'll need to do the cycle 2012 times, 2006 = 2006... etc....
3DS games that have gyroscope features will have their gyroscope features disabled because the DSi has no such hardware.