epimitheas, thank you for the start! However, I don't see anything translated in VirtualBox_el.ts, it even lacks your name. I've added your name and the language name myself but keep in mind that the translation won't be added to the distribution until the amount of translated items reaches the 50% limit (note that you must take both .ts files from SVN and continue your work on them, not on your local copies!). Also, you didn't provide us your email which is a requirement too.
Pau, I've merged your update however could you please comment on what are the other two archives attached by rbuj after you?
rbuj, thank you but first please tell what did you attach and why and who you are :) The Catalan translation is maintained by Pau Iranzo now so you should coordinate your efforts with him. I left your files untouched so far.
Updates to the Greek, Slovak (Qt3), Catalan (but not ca_2 and ca_ES), Romanian, Czech and Chinese are merged to SVN.