Unfortunately there have been a number of concerns over hCalendar's use of the abbreviation design pattern. This uses the HTML abbreviation element to add machine data to pages. Our concerns were:
the effect on blind users using screen readers with abbreviation expansion turned on where abbreviations designed for machines would be read out
the effect on partially sighted users using screen readers where tool tips of abbreviations designed for machines would be read out the effect of incomprehensible tooltips on users with cognitive disabilities
the potential fencing off of abbreviations to domains that need them (travel - airport codes, finance - ticker symbols etc)
Until these issues are resolved the BBC semantic markup standards have been updated to prevent the use of non-human-readable text in abbreviations.
They also go on to say that they will be considering the use of RDFainstead ofMicroformats. I've toyed with the idea of adding Microformats to my sites. I have a few sites that use them, but I haven't seen much benefit.
i've got them on my site as well, had them on for ages now. i've never seen much benefit either, to be honest. but i think you have to be a specialist user to appreciate them at the moment (ie, a geek).
if you know they are there, then they can be quite handy. i've got the usual kind of stuff -- a load of geo-codes which can take you straight to google maps, and hcards which you can download into your address book -- but unless the user goes out of his way to get the necessary plug-ins and firefox extensions that can take advantage of them, then they as good as useless. but then again, they don't do any harm either. and the code required to put them in place is hardly difficult, so i don't see much point in taking them off.
that disabled stuff that the BBC is trotting out is all well and good, but those problems would be very easily solved if microformats took off. the makers of these screenreaders could easily just stick something in that recognised what is was, and amended the speech accordingly. and the same with the tooltips. microformats are more or less standardised already, so the class names would be identical across all sites.
i've also got some hreviews on my site, which might take off one day when the search engines finally get around to gathering together all this kind of stuff.
but when you've got sites like the BBC going backwards with it, it gets harder to see when that day is going to arrive.