For those who needed (or just wanted) to open and edit MS Word or Excel files on their iPhone/iPod touch (iPhone OS 3.0 & up), Documents-to-Go was the only way to go till recently. But now there's Quickoffice Mobile Office, a fullblown suite that Macworld rates as 4 stars. Some caveats: you can open and edit both Word 2003 and Excel 2003 files, but you can only edit the older Office 2003 format, not the newer Office 2007 format (used in Office 2008 for the Mac). Editing tools are many and "deep". Files can be uploaded to a public folder on MobileMe, or emailed via the Quickoffice e-mail address.
The app also opens Powerpoint files, but not OpenOffice ODT files, and "provides the most flexible options for getting files onto the iPhone, whether by mail attachment, through MobileMe, or as an upload from the Mac Safari browser."
(Macworld) | Cost: US$13 | For further info...