Can iWork / Numbers on the iPad open and/or save Microsoft Excel (.XLS) files?

Numbers, iWork's spreadsheet application can import Microsoft Excel files but cannot save them.

Outbound spreadsheets in iWork can be saved in either Numbers or PDF format, but not Microsoft Excel format (.xls).

However, Numbers spreadsheets created on the iPad can be uploaded to iWork.com where individuals on either a Mac or a PC can view them.