A short report from last September from the Centre for Cross Border Studies was missed here at Borderlands HQ. The CCBS is one of the biggest hitters in cross-border co-operation research and has produced a huge amount of material on the Ireland-Northern Ireland border situation. At least, that's my excuse for missing this briefing paper first time round.
The report (http://borderireland.info/discuss/?p=98) focuses on co-operation among public libraries on the island of Ireland, where formal co-operation goes back over 30 years. There are lots of good cross-border project examples included in the report, with the key conclusion being why has this been possible for libraries, but not for other public services.
From a wider perspective, it would certainly be worth looking at whether any of the lessons could be transferable elsewhere in Europe - or indeed whether there are good practices out there waiting to be discovered. Evidently, where there is a common language on both sides of a border, it would make library co-operation more desirable, but it would not be a pre-requisite. This Canadian-US example is probably quite unusual, but is very positive (until the Department for Homeland Security builds fence through the middle of the building): http://en.wikinews.org/wiki/Canada,_U.S._to_tighten_security_between_'cross-border'_library