There is not a requirement for Sun to provide an upgrade exam from the current SCBCD to the new one, but I would imagine that, like the other exams (SCJP and SCWCD) they are likely to offer one. Especially in light of the apparent increase in the testing fees.
As to the comment regarding the 'free' exam - it's a beta test, meaning that we're trying out the questions that they are considering offering on the real thing, rather than having it be an actual representation of the testing experience. The real exam will offer a more 'reasonable' number of questions (probably in the range of 50-70) with a shorter time limit (probably around 2 hours). The benefit to taking the beta is that you get the chance to test-drive the exam for free a few months before it's offered to the public.
Theodore Jonathan Casser
SCJP/SCSNI/SCBCD/SCWCD/SCDJWS/SCMAD/SCEA/MCTS/MCPD... and so many more letters than you can shake a stick at!