See also Orca bug #480998 which is blocked by this issue.
http://bugzilla.gnome.org/show_bug.cgi?id=480998

Sample oocalc fruit.ods available at:
http://bugzilla.gnome.org/attachment.cgi?id=96294&action=view

Steps to reproduce:

0. Start Orca
1. Start 'oocalc -norestore fruit.ods'
2. Type Control-Home to position the text caret in cell A1.
3. Press the down arrow to move to cell A2.
4. Type Insert-f to get text attributes on the current cell (A2).
5. Press the right arrow to move to cell B2.
6. Type Insert-f to get text attributes on the current cell (B2).

What you should get at step 4 is:

SPEECH OUTPUT: 'size 16'
SPEECH OUTPUT: 'family-name Arial'
SPEECH OUTPUT: 'bold'
SPEECH OUTPUT: 'style italic'

What you should get at step 6 is:

SPEECH OUTPUT: 'size 10'
SPEECH OUTPUT: 'family-name Arial'

Instead, nothing is spoken.

I did a bit of debugging from the Orca end.

From the Orca debug at:
http://bugzilla.gnome.org/attachment.cgi?id=96723&action=view
we can see that doing an Insert-f when
focus is in cell A2, results in the following debug message 
(at line 1310) in the readCharAttributes method in default.py:

readCharAttributes: default text attributes:

The role of orca_state.locusOfFocus is ROLE_TABLE_CELL

Printing out orca_state.locusOfFocus.childCount gives a value of 0.

After adding extra debug to readCharAttributes of the form:

            objectText = self.getText(orca_state.locusOfFocus, 0, -1)
            print "objectText: ", objectText

we get:

objectText:  Good in Pies

But

    defAttributes = text.getDefaultAttributes()

is returning an empty string here.

Looks like oocalc doesn't provide text attributes for the text in 
spread sheet cells.