Client Portal has a new capability. You can permit clients to view the notes and time entries on a ticket.
When the option is enabled, clients can click on a ticket to show the ticket's notes and time entries.
To show these notes, enable the "Show Notes and Time Entries" field on the board edit page, Portal tab.
Internal notes are never shown, even if this setting is enabled.
Missed the announcement about Client Portal? You can read about it here.