The deadline for Harvard and NYU is approaching. I've sent the recommendation letters and official transcripts according to the instructions of the schools earlier, but I haven't submitted the on-line application to schools - still working on my Personal statements. However, a friend told me that most schools required applicants to sign a print-out version of confirmation letter and thereafter send the letter via mail. Is it true?

No, you don't need to do this for Harvard (dunno about NYU). They ask you to sign your name electronically on the personal statement you upload.

You do not need to do this for NYU either.

It used to be like that last year, now they have switched to an entire online appl.