I’ve changed the date heading for each post to display the relative time since the entry was posted, rather than absolute the date and time. My main reason for doing this is that it solves the timezone problem; all times on this site are in GMT, but the majority of the site’s visitors are likely to be in different timezones. Showing the time elapsed since the entry was posted serves everyone regardless of their location.
Rather than write my own function for this, I have reused the one written by Natalie Downe for her own blog, which she launched a few days ago. She has described its workings in some detail in her most recent entry.