[ruune]

The border problem in Ireland was originally settled by a border between Northern Ireland and the rest of the UK (until the UK found it didn't like what it agreed to anymore). I'm really not an expert on anything in that field, but a border between Scotland and the EU similar to the Northern Irish one should resolve that problem, making Scotland able to join the EU with an open border to the UK, no?

[petesergeant]

The movement of people isn't really a big deal due to the Common Travel Area (which you've got to assume an independent Scotland would be in). But movement of goods would be a huge problem, as Northern Ireland is showing right now.