Simple answer: Yes, AMCAS will send your newly released MCAT scores to the schools who are waiting for the results from your "future" MCAT date.
Not exactly sure how it happens, but from what I've heard, it appears to be a pretty seamless transition.
I also found the following post on the web. Although a bit dated, it may be relevant to your original question. Maybe not. Hope this helps.
Q - Can I submit the AMCAS application without having a MCAT score? 4/24/07
A - Yes, applicants can submit the AMCAS application without having an MCAT score. Applicants will need to indicate on the application when he/she expects to take the MCAT. The AMCAS application will be processed without the MCAT score and schools will be updated once an MCAT score is received. If the applicant indicates that he/she is taking an additional MCAT exam during the application cycle, schools will likely wait until the new MCAT score becomes available on AMCAS to send out secondary applications.
For applicants who plan to take the MCAT for the first time or are retaking the exam during the application process, the following is the exact question as stated on the AMCAS.
"Have you taken, or do you plan to take the MCAT in calendar year 2007 from May to September?"
If the applicant answers "yes" he/she will be brought to the next screen where they will identify the date in which they plan to take the test from a pull down menu with the dates pre-populated.
It is very important to note that the applicant can and should change their answer at ANY time throughout the application year including applications that have already been processed. Typically, medical schools will use this information to decipher when they should start reviewing the application with the MCAT scores.
