Do you think this is just piped row by row?  Looks tedius if it is.

Yes, and I agree.

I agree with AnnieCahill - it is piped on.

From what I can make out in the picture - but can't be sure, is that it looks like a number 2 plain tip or bigger was used for this effect.

That looks like a lot of work! If you could get a cutter in the correct shape, you could always cut out the shapes and ice each one individually over a period of time and then attach them at the last minute?  No less tedious in the long term but at least it would break up the work a bit and gurantee that the pattern is correct.
 

Would it not be with a rose petal tip in little ruffles?

looks like small rose tip in little ruffles to me also.  Once you had the basic arches laid out the little ruffles would probably go pretty quickly.

Thanks.  Just today I happened to see a similar cake on Martha Stewart and it says they used a petal tip!  Obviously, there are variaions.  I think it could be done with more of a flat sided to look like "ribbon" as well.