It looks like Microsoft let a little fault slip by while it was working to bring Office to the iPad. Regular users need not worry - it's hardly something that would pop up in the middle of an intensely heated, extra fun spreadsheet-on-a-tablet session. Not-so regular users that rely on SharePoint 2010, however, are facing an obstacle. The problem is that Microsoft's collaborative editing platform relies on ActiveX controls to access documents, and these are a famous no-go on iOS. As you may remember, Apple chose to move away from technologies that rely on plug-ins, like Flash and Silverlight, early in the iPhone's history.
Thus, users that try to open a document from a SP 2010 Document Library, will be greeted with a soothing "there is no SharePoint Foundation application available to open the app.” message.
Luckily, there are workarounds. Fresh-faced Office for iPad users can either "Add a Place within the application that will connect to the SharePoint Document Library", or download a copy of the file. If the language doesn't make sense to you, both solutions are detailed in the source links.
To Microsoft's credit, the company published these workarounds the same day the product launched. This means it was aware of the issue and presented existing solutions as quickly as possible. Hopefully there aren't other mishaps, or at least such that will catch both Microsoft and its customers unprepared.