From the Lotus Notes / Domino 6.0.5/6.5.4 Fixlist:
SPR# FSIZ64VPP4 – Starting in 6.0.5/6.5.4, the term „Task“ will replace „ToDo“ to be consistant with Microsoft Outlook.
Who is actually the leader in the messaging market?
Update 06.04: I was wrong. This is for Domino Access for MS Outlook only- and it makes obviously sense.