These haven't really changed much from last year, with a few notable exceptions, but I noticed they were printed in the pocket meikan I bought today, so here you go:
Fighters: 「熱く、頂点（サミット）へ」 ～F・A・N・S ’０８～
("Atsuku, chouten e!" "Burning, to the summit!")
It's unclear to me whether they want to use "chouten" or "summit" to be honest. I'm sure if Hillman was still around they'd use the English word.
Marines: 「A Passion for Our Dream, a Commitment to the Flag ～夢に情熱を、フラッグに誓いを～」
("Yume ni jounetsu wo, FLAG ni chikai wo". Pretty literal translation.)
("Mezase sekai ichi!" Again, no official English version, but they've had this slogan for four years now... effectively "Aim to be the best in the world!" It's also the Softbank company slogan in general, I believe.)
Rakuten: 「Smart&Spirit 2008 考えて野球せぃ！」
("Kangaete yakyuu seii!" which pretty much means "Thinking baseball!")
Seibu:「No Limit! 2008」
Orix: "One Heart Beat" ～鼓動をひとつに～
("Kodou wo hitotsu ni")
Giants: 「Show the Spirit-奪回-」
(It's the same as last year. That last part is pronounced "dakkai" and means "recapture". Technically, dakkai is the slogan, and "show the spirit" is the catchphrase, but whatever.)
Chunichi: "Road to Victory"
Hanshin: "Be the Best For the Fans" ～最高をめざせ！ そしてファンのために！～
("Saikou wo mezase! Soshite FAN no tame ni!" literally "aim for the best! For the sake of the fans!")
Yokohama: 「なせば成る～Move on～」
("Naseba naru" -- same as last year)
Hiroshima: "All-In 激"
激, pronounced "geki", sort of means... violent/excited. They refer to a 激戦, a gekisen -- hard-fought battle -- as the way the Carp will play this year.
Yakult: 「Dynamic & Dramatic 躍動感あふれるプレーでファンに感動を！」
("Yakudoukan afureru PLAY de, FAN ni kandou wo!" I do think it's some sort of play on having doukan and kandou, but maybe I'm just reading more into it)
It doesn't make much sense literally in English, kind of like "Vibrant overflowing play, fans are deeply moved!", so I'd like to take poetic license and turn this into "Play bright, EXCITE!"
Yeah, I know open-sen has started. Unfortunately, even if I wanted to translate box scores, I'm not sure where complex ones are. The best ones I've seen are on the official site and even those are just simple boxscores, not events like Yahoo usually has. Alas. Even if I wanted to, though, I've just been running into weird troubles with Japanese text. I'm now running Debian on my USB stick, but it's still something of an adventure. No hard drive? No problem!