Not sure if anyone's done this before, and I'm partially making this post to find out, and also to let you guys know that: Yesterday, a group of Bards and Co. have found it is possible to board other ships. I haven't heard of anyone doing this previously, but basically, if you pull 2 Junkers up along side each other on a certain angle, and at a certain altitude, it's entirely possible to board an enemy/ally ship before the game pulls you back on your own boat.
Again, sorry if this isn't new, but even if it's not, I want people to be aware that it's A) possible and B) In the game's coding
EDIT: Other people have done this, so... If you didn't know about this wholly useless tidbit, great
Now you do. If you did, sorry about that