Many websites have their logo near the top which is a clickable link to the homepage. There's some interesting discussion about this kind of button in this question. I am wondering if it's a good user experience to make clicking the logo reload the page while you're already on the home page, or if it should be a link that does nothing.
In the past, linking from a page to the same page, without a target anchor, was a definite design error (http://www.nngroup.com/articles/113-design-guidelines-homepage-usability/), because it just reloaded the page and nothing else, which is a waste of time and there's an expectation that a link do something more.
But this design error, in the form of the logo on the home page linking to the current page, and similar nav link linking to the current page, has become well engrained in the vernacular of web design to the point where it's often not considered an error these days, although it shows an inattention to detail. If reloading the page accomplished something useful, like updated content, then a link-to-the-current-page is a less egregious error, but if it simply reloads the page it is a definite design flaw.
Generally it's still best to not link to the current page (except for anchor targets), even if it serves as a useful shortcut to page reload. The disabling of logo-home link serves as an indicator that they're already on the home page, so it gives the user useful information and is logically consistent.
Why shouldn't clicking the logo reload the page?
A link that does nothing seems like more of a UI problem than a link that reloads the same page.
If a page has any time related content like feeds that do not auto-refresh, just like the question list pages on this site it would be very ill-advised not to refresh the page when the logo is clicked. Even when a "feed" page has a notification feature, such as this site's question list pages or twitter, that can be broken by your computer going to sleep. Reloading the page is then the only way to get it going again.
Clicking the logo is a very well-known "reload" "gesture" that should not be messed with unless you have very good reasons.
And it is not just the logo. any link that refuses to do what you expect it to do is an UX problem. Even for pages that do not have (frequent) updates.
Take GMail. Yes it has a notification mechanism and yes, it auto-displays new arrivals. But that mechanism isn't foolproof. Even so, GMail in all their wisdom decided that clicking the "inbox" link should no longer reload the inbox' contents. Totally annoying that it refuses to reload the inbox because it thinks it knows better than I do. It often gets it wrong refusing to reload when I know for a fact that it has because my phone has already whistled at me.
I understand that gmail may have opted to do this to reduce the load on their servers because people may have been clicking the link just to check that no new mail arrived, but it still annoys the heck out of me to have a link not do what it is supposed to do. Twitter even goes further: it even disables the F5 key. Grmpf.
So, basically, unless you have very, very, very good reasons to "know better", just do as asked.
For many first timers visiting a site, while browsing, they get lost and do not know where they are, or even that the page they are on is actually the home page. And if the home page logo is disabled, it would seem that it is not working. So unless you have a very indicative design which shows that you are on the home page, I think it would be better to not disable the logo, even if it does nothing new.
Yes it could reload the page, but think of the uses cases that would result in someone clicking on the home button while on the home page.
If the analytics/user tests reveal that is indeed what people do. Perhaps you could have it trigger something a bit more exciting. For example Indicate you are already on the home page and offer share buttons.