Hi Su,
I tried it and it does allow me to format.
1)From the Controls Task Pane,add a repeating table to your design.
2)Now Select a field(field1) in the DataSource Task Pane and double click to open the "Field and Group Properties" dialog.
Change the datatype to "Rich Text(XHTML)".
3)As soon as u change the datatype,the corressponding control in the InfoPath design shows a red symboled warning stating "field1(control cannot store this datatype)".
4)So Delete that control from the repeating table and drag the field1 from the DataSource task pane to the repeating table.
5)Now preview the form.
6)Enter ur name in the rich text box and try all possible formatting including indenting,line spacing,coloring and so on.
It works.
Regards,
Abhishek