I have three weblogs running WordPress from different directories on the same hosted server. Two of the three showed the 2.7.1 upgrade as available. They both automatically updated very quickly and without issue.
The third still shows 2.7 as the current version - it hasn't presented me the opportunity to update, even when clicking Tools - Upgrade. Not sure what might drive the one not "seeing" the update. Once it is available the update process works well.