I've just upgraded the Silverlight Toolkit libraries that I'm using to the December 2008 version.
When reocmpilling my Online Calculators project I discovered that the DynamicSeries type had disappeared but it wasn't listed in the changes section so I had to hunt around for it. I compiled the Toolkit's source and then searched all the files for DynamicSeries and found it left in one of the comments and it appears to have been replaced by the DataPointSeries class.
Replacing the DynamicSeries references with DataPointSeries references got the project to compile and it appears to run correctly.
There has, however been a performance degredation in the auto-updating of the charts in the Mortgage Calculator so I haven't deployed this yet. I'll try and take a look at what's happening and try and optimize my code and see if I can get it back to the current speed before deploying the new libraries.