Regarding the size difference between the OTA update and the leak's PB00IMG.ZIP, read this post describing how an OTA update is different from an RUU:
FYI: OTA URL capture - xda-developers
If you ran the RUU for MR1 or MR2, it created a ZIP file on your memory card that was about 100MB in size, even though the OTA update was only 5MB or so. Why? Because it flashes the whole ROM instead of just updating the changed parts. The OTA, on the other hand, changes only the files that need to be changed, hence it is always smaller.
I'm starting to agree, based on the reports of the people who've received the OTA, that it is in fact the same exact software as leak v3. The slight differences in the "list of improvements" sound like marketing errors; they were copied from another phone's paperwork.
If what I'm saying is true, then a) the file eventually posted on PCDphones.com will contain the same image files as leak v3, and b) those of us with the silent phone bug will still have it (and many of our 1.5 brethren will join us in having it, and we'll need to have our phones replaced in order to solve it).