i get a message when trying to sort by date saying 'no shown packages currently have the required information for sorting by this criterion. the list is unsorted' is this just me or does everyone get this message?
Package date fetching is an experimental feature, it needs to be enabled from the options menu first. It is only done for packages from maemo.org repositories and only for user/* category packages. The first fetch can be quite slow but the dates are cached for later use and only dates for new packages are fetched next time. Packages that are already installed always have their installation date information with them.