Carlos,
it is wonderful that you are going to be able to come. Due to the nature of Heidelberg (small, ancient, beautiful, and packed into a tight valley) there are a lot of small hotels and lots of tourists. We have added more information to this page: http://dotlrn.org/events/2004-heidelberg/ on lodging. The most efficient way to find a hotel at this point is to call the visitor's office and having them help you reserve a room (I talked to them just this afternoon and there are still rooms available and they are happy to give general info in addition to actually reserving the rooms +49-6221-142224).
We also put up some more event registration pages where you can sign up for additional gatherings (e.g. Dinner). At this point it is important to sign up for the .LRN event and/or OpenACS event so that you will receive general bulk mails we might be sending out as the dates approach.
Sign up now (e.g. our social coordinator has organized two dinners at two different Heidelberg breweries where spots might be limited).
I will be working with Sloan on getting up the specifics of the .LRN meetings this week, with a preliminary posting of "the source" of the agenda here for suggestions and modifications.
