Thanks to the question on checking SNCF trains during a strike, I was able to discover that one of my trains today was cancelled. Sadly though, the only alternative involved a very hefty delay and an unexpected night in Paris...
Normally, one would be able to reclaim 75% of the cost of the ticket for a delay of 3 hours or more, under the SNCF Garantie Ponctualité. This would go some way towards the hotel costs, even if not really covering the inconvenience...
However, I'm not sure if that still applies if the cancellation was due to a strike. Are you able to claim under the SNCF Garantie Ponctualité for delays caused by cancellations during a strike, or is that excluded?