I haven't received any emails notifying me so I guess others haven't either. Smith Micro have released an update for Manga Studio taking it to version 5.0.5 which you can download here (you may*** require your serial number):
manga.smithmicro.com/updates.html
EDIT - *** Replace the word may with the word will, and follow the words serial number with the words name, address, phone number, email address, medical history, marital status, and pretty much any other information that really shouldn't be necessary to download a free update to software you paid for when they already had that info when you registered, GRRR
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