I've had the same problem with Pages on my iPad3, twice today, just typing away normally and then it drops out. You can't report the problem to apple in the same way you can when it crashes on OSX which is annoying. Out of curiosity I thought to fire up Xcode and see if there was anything in the logs, i found this:
Mar 27 15:26:17 unknown sandboxd[25] <Notice>: Pages(83) deny file-write-data /private/var/mobile/Library/Mobile Documents/com~apple~Pages
Mar 27 15:26:21 unknown Pages[83] <Warning>: *** Error: -[TSPDatabase startSingleResultQuery:error:] TSUDatabase.m:231 Executing query and expecting exactly one row: "pragma user_version": disk I/O error (266)
Mar 27 15:26:21 unknown Pages[83] <Warning>: *** Assertion failure: -[TSPDatabase dealloc] TSUDatabase.m:70 Database wasn't closed
Mar 27 15:26:21 unknown Pages[83] <Warning>: *** Error: -[TSPDatabase closeWithError:] TSUDatabase.m:96 Finalizing statement: disk I/O error (266)
Mar 27 15:26:21 unknown Pages[83] <Warning>: *** Error: -[TSPObjectContext _initWithPath:isNew:emigrationDestinationContext:rootClass:errorDelegate:] TSPObjectContext.mm:1129 Couldn't create object context at path (/private/var/mobile/Library/Mobile Documents/com~apple~Pages/Documents/*** My Filename ***.pages-tef). Error: Error Domain=com.apple.iWork.TSPersistence Code=1 "An error occurred while reading the document." UserInfo=0xc6461e0 {TSULocalizedErrorAlertTitle=An error occurred while reading the document., NSLocalizedDescription=An error occurred while reading the document.}
Mar 27 15:26:21 unknown Pages[83] <Warning>: *** Error: -[TSADocumentManager _openDocumentForInfo:animated:] TSADocumentManager.m:612 Unable to open document *** My Filename *** located at /private/var/mobile/Library/Mobile Documents/com~apple~Pages/Documents/*** My Filename ***.pages-tef
Mar 27 15:26:34 unknown CommCenter[15] <Error>: Activating PDP context 0, because it has assertions and is now available for use.
Mar 27 15:26:34 unknown CommCenter[15] <Error>: kDataAttachStatusNotification sent, wasAttached: 0 isAttached: 1
...the disk io error is a bit of a concern, this ipad is only 5 days old! If this keeps happening it's going straight back to apple!