In reply to cham749:
I was there for the first 2 weeks of March 2010. Conditions were fantastic; fat ice and dropping well below freezing every night, but not too cold as to form brittle ice. My friend had been out in early March 2009, when conditions were even better.
As with last year, things don't bode well for this coming March though, at least not at the moment. I think I'd have a Plan B.
Rjukan itself in the rain must be grim. Before my first visit, my friend told me: "the town is a sh1t hole; its only the snow and ice that makes it look pretty". On reflection, she may well have had a point!