eVeNtInE, look at the previous pages of this thread, and you'll see we've already discussed the translation features for Marvin in some detail. Kris said he'll likely incorporate a dedicated button to take you to the Wictionary translation of the word, and another button to launch a 3rd-party, external dictionary app from within Marvin. I recommend the Lingvo app to you -- it features lots of top-quality dictionaries, from top publishers like Collins, both definition dictionaries and translation dictionaries for many language pairs.
WordReference could be something for Kris to look at, in addition to Wictionary.
We haven't mentioned Google Translate so far, but actually that's a great idea.
Maybe Kris can come up with yet another (dedicated but optional) button for Google Translate within Marvin.
Although the quality of translation, especially of entire sentences, tends to be very poor in Google Translate, the service can actually be useful for getting a (very) rough idea of what a stretch of foreign-language text says.