Sidhekin's methodology is better. Nevertheless, here is my take. 33 chars

    #23456789_123456789_123456789_123 (33)
    s/[^.]+.\s*/\u\L$&/g;s/\bi\b/I/g;


    # Or for cases with leading whitespace

    #23456789_123456789_123456789_1234 (34)
    s/\s+|[^.]+./\u\L$&/g;s/\bi\b/I/g;
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--
John.