Jeff,
If you are doing a lot of this, here is an AppleScript that will change the text case in multiple selected cells.
--select range of cells in Numbers, run, changes text case
--change as desired to: "upper" "lower" "title" "capitalize"
set caseType to "title"
tell application "Numbers" to tell front document to tell active sheet
set selectedTable to first table whose class of selection range is range
tell selectedTable
set selectedRange to the selection range
tell selectedRange
repeat with i from 1 to count of cells
set thisValue to value of cell i
if thisValue is not missing value then set value of cell i to ¬
(do shell script "/usr/bin/python -c \"import sys; print unicode(sys.argv[1], 'utf8')." & caseType & "().encode('utf8')\" " & quoted form of thisValue)
end repeat
end tell
end tell
end tell
--end of script
This changes the actual text, not just how it is displayed in Numbers, so it won't "revert" your subsequent manual changes. To use, select the cells first, then run.
SG