Using Creative Commons licenses for spatial data?

There is no problem with CC in general except when people use the optional share alike licence eg. OSM. http://creativecommons.org/licenses/by-sa/2.0/

It is quite common to want to mix copyright data that you can use but have no right to apply the cc licence to. So in not allowing derivatives that are copyright but with attribution, share alike renders such data incompatible. Some people have used layers in mashups to try to get round this but it is very shaky ground legally. Due to the number of people involved it is not usually possible to go back to them and negotiate a different licence for a particular use and in the end it means that companies won't touch it.

The aim is to force people into sharing their own work but in real life people get datasets from a variety of sources and the end result is that it simply reduces the number of people getting involved.

Another possible problem is datarot when creative commons data is released as no derivatives allowed.

This means that:

Licensees may copy, distribute, display and perform only verbatim copies of the work, not derivative works based on it.

This becomes problematic when errors are discovered in the dataset, or it needs updating in any way. If the copyright holder is not contactable, or a disinclined/too busy to maintain a dataset, it becomes less and less useful over time.

The problem is that in some jurisdictions (in particular the EU) copyright is applied differently for databases than for coherent single works of creation. Therefore, it was necessary for i.e. openstreetmap to work on a new licence that would cover these different ways how copyright law is applied in a way that the ideas of creative commons are also valid for information put in the form of a database.