Come do strange things with computers amongst others whilst drinking fine Portland beer. Look for the row of geeks with computers in the back of the main room. The meeting schedule can be found on Calagator.
All programming languages welcome. Come work on your own projects, work on others participants' projects, get advice, have fun, etc.
You're encouraged to bring a computer, but can team up with others that brought one too.
Afterwards, the group descends on the 12th and Hawthorne foodcart pod for additional nourishment.
Also, many people meet up at the pub during the same time as the hackathon to play boardgames they bring which you're welcomed to play.