Trials and Tribulations is slated for a May 2010 release on Wiiware according to gamefaqs. One thing I can tell you is that I am pretty sure there are no spoilers in Apollo Justice for Trials and Tribulations (even though AJ
does have very significant story stuff for Phoenix).
Cag, if it matters trials and tribs is my favorite in the series. IMO the best fillers, and the "main plot" is the most convoluted yet the best of the games, taking up a new plot for the first and fourth case of the game and then merging that with threads from the first two very effectively (and, from what I could see, nary a plot whole to be found!). Additionally, both cases 1 and 4 are entirely courtroom-based, which I tend to prefer over the investigation parts of the cases.
I also like Apollo Justice, the 4th game in the series, quite a lot. A fair number of fans seem to dislike it, and the most valid claim IMO is that Phoenix (who is not the main character) ends up being more compelling and developed than the new lead. On the flip side, I feel like something about the game (probably the courtroom music, which I felt was the best of the four) caused the trials to feel a little more intense, even when they were...wacky.
Also, because Justice for All and Trials and Tribulations were made before case 5 of the DS Phoenix Wright: Ace Attorney (it was a new case for the DS port) they contain no references to that case. But Ema Skye returns, taking the place of Gumshoe of all people (she failed her forensics tests...

) and I liked her new character a lot. (if you know the character archetype "tsundere", she is 100% "tsuntsun" and no "deredere")
I never got into the mystery/adventure sort of thing.. but I LOVE RPGs.. I was the biggest fan of Disgea for a long time, but it's jut TOO big.. TOO unlimited.. So along similar lines is Final Fantasy Tactics: A2 (which is awesome) but nowhere near as good as the Luminous Arc series. LA looks a tad dated though, but the storyline, plot and humour well make up for it. LA 2 looks fantastic. It's funnier and more engaging than the original, and they've made the combat even better. Luminous Arc 3 should be released later this year, so I'm holding my breath for that!
I have to admit, I tried LA but never really got into it, so I didn't even dl the second one. As for disgaea, I have to say that even though the original has a high status in my mind, most of the other NIS games I have played do not. Sometimes they have better gameplay (phantom brave had a no-grid turn based move system that was pretty fun to explore) but the stories...tend to be not very funny, or feel rather forced when they are funny. Disgaea had some kind of charm the others don't seem to...
One TBS I enjoyed recently was Devil Survivor. It's grid based in terms of movement, but when you "attack" another unit, it initiates a turn based battle (almost always a 3-on-3 fight) which lasts for 1 or 2 rounds. Your ability to get extra turns is based on whether you use effective attacks against enemies as well as stuff like agility (you can also get an extra turn if the enemy uses an ineffective attack against one of your characters, or lose an extra turn if they use an effective attack against you).
It's part of the megami tensei series, so the monster designs are ridiculously awesome; you can eventually get bishamon (buddhist war god), metatron (god's voice), and all sorts of other cool cats to help you out. And like any megami tensei game (heck like any JRPG) the game is primarily centered around kill/become/find/ god type stuff.