my ears must have been burning...

OMF is a file format that Avid came out with in the early 90's. Since Avid owns Digidesign (ProTools), the file format became a popular method for video guys to send projects to PT guys. The format itself is pretty limited, but it will save basic fades, volume, pan, audio files and their placement. Keep in mind that there are lots of limitations with OMF, so projects don't always get exported the way you expect. (ie: linear crossfades ONLY; some programs don't import panning)

SSL's ProConvert is the absolute best way to convert from one project format to another. I convert from Nuendo (almost identical file format to Cubase) to Pro Tools all the time. But I should also mention that ProConvert costs almost as much as Cubase. (about $600)

The best time-tested (and free) option for moving from one system to another is to bounce down each individual track. You should have a macro in Cubase that does it automatically for you. Then all the other guy does is line em up at the beginning.

Come to think of it, you should also try two other formats for exporting. AES32 was designed (partially unfinished, i believe) as a free/public project file format. I believe logic and cubase can import/export that way. I haven't used it, but you should test it out with your buddy and report back to us.