Call me a fanboy or what have you, but I just love my PS3. I've got plenty of games to play on it, and it's probably the best console to use when you're trying to learn Japanese. Dale would suggest just building yourself a custom Media Center PC, but since I've already got the console, and am already strapped for cash, I figured I'd just go ahead and use it.
This post certainly isn't meant for those just starting out in Japanese -- I'm assuming that you've got at least a year, if not two, of Japanese study under your belt. We're dealing mostly with watching TV shows and heavy kanji reading.
So, let's get this show rolling and see how Sony's giant behemoth can be used to help you practice Japanese. With the power of Blu-ray and the Cell processor behind it, you'll be fluent in no time!
One of the first things I would ecommend doing is replacing the system's hard drive. It's relatively painless and inexpensive -- for $90 or so, you can put a 320GB hard drive into the system, which will give you a great amount of space to work with, and turn the PS3 into an easy-to-use Media Center. Of course, if you don't want to pay the money, you can always just stream the files from your PC. Many of the untranslated and unlicensed anime files that are released online are encoded in formats supported by the PS3, so you won't have to worry too much about converting files over. If not, then just plug them into a free conversion program like Red Kawa.
The idea here is that now you have an opportunity to just sit in front of the TV and watch anime, J-dramas, movies, and just about anything you can get your hands on. What's so special is that you've removed the computer from the equation, meaning that you can't be distracted by IMs, Internet forums, the Japanator IRC channel, or anything else. It's just you, the TV, your notebook, and a dictionary.
Here's an exercise for you to try: watch a show all the way through, and once it's over, write down a summary of it. What happened, who all the characters were, etc. Then, watch the show again, but try and take more detailed information as things go along, like writing a summary after each scene (whenever the location changes). Sure, it isn't anywhere near doing your own fansub, but if you're capable of doing that, there isn't much reason to be reading this, is there?
Moving onto the games themselves, the PS3 is region free, allowing you to import whatever titles you might want to play. The games give you a chance to interact with the Japanese, so you become more familiar with menu options and get virtual feedback to your Japanese knowledge. When you're put into a situation where you've got to react quickly, you'll pick up some of the kanji subconsciously, so that you can recognize it, know what it does, leaving you to just learn the meaning. So, whether it's Metal Gear Solid 4 or Mainichi Issho, you'll have endless chances to play Japanese games.
A special note on Mainichi Issho: the game is fantastic. You're put in a low-stress environment where you can just play around, read broadcasts in simple Japanese, and look at cute things. Topher had really been pushing me to download the game, and once I did, I saw why. Over here in the US, we really don't get to see the cuteness of Toro, Sony's cat mascot. One of the great things for those who have a limited vocabulary list, you'll run into plenty of household items as you decorate your place, and visit others, so you'll be able to pick up the names easily.
There are plenty of possibilities when it comes to using your console for educational purposes -- whether it be as a Media Center, as a teaching tool, or as a place to chat with Japanese gamers while playing Resistance or Winning Eleven. There are plenty of things to do with your PS3 besides just playing games. Use it to learn, to socialize, and to make yourself a better person.
I've done a good bit of streaming anime from my PC to my 360, it's easy to set up (same for the PS3).
Mainichi Issho being text based is far too advanced for me unfortunately (although the MGS gags were nice in the vid).
I've bypassed the whole Media center thing as my PC is right next to my TV i just plugged my PC straight into that, which is nice it's what I watch all my drama's/anime/movies etc.
Imported a load of PS2 games, haven't done the same with any PS3 games yet. Mainichi Issho looks interesting tho, and I'll probably import White Knight Chronicles.
Basically the same as JellyDoodle, except my PC IS my TV, since I've got a capture card, and one of my monitors is connected to my 360 via the VGA cable you can buy, so I can have one screen on my computer and one on my 360 (it makes it easier to transfer files and stuff if I want to keep from sharing ALL of a folder - university networks are pretty insecure as is so I try to refrain from that). The only downside in my situation from the PS3 is I need to convert video files, but with all the video editing I do that isn't hard...
Sidenote: the site you linked to also has a converter for Xbox 360 - http://www.videora.com/en-us/Converter/Xbox360/
Mainichi Issho being text based is far too advanced for me unfortunately (although the MGS gags were nice in the vid).