There are various compensation rules for long-distance trains, both cross-border and national. Quick googling got me Deutsche Bahn.

There are various compensation rules for long-distance trains, both cross-border and national.

Edit: The compensation rules for Deutsche Bahn can be found here. They explain compensation for delays of more than one or two hours, follow-up transportation in case of missed connections, and reimbursements for overnight accommodations.

The page also has some links on Europe-wide and other European regulations.