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<div>There's been recent activity in the OWL community aiming towards
extensions which provide OWL DL with increased expressivity.
(There's also work ongoing around subsets of OWL that are closer to
RDF, but that's a different story - check these posts from 
<a href="http://www.mindswap.org/blog/2006/11/11/an-alternative-view-for-owl-11/">Jim
Hendler</a> and 
<a href="http://www.lassila.org/blog/archive/2006/11/more_on_rdf.html">Ora
Lassila</a>).
The main proposals are captured in the 
<a href="http://owl1_1.cs.manchester.ac.uk/">OWL 1.1</a>
specification, although it should be noted that this as yet has no
official standing, and "1.1" is just a working title. There are
several significant additions, and the primary specification is
done in an different fashion than OWL (with a new Functional-Style
Syntax).
Personally I'm skeptical this is the right time for any major
overhaul of OWL (like, 
don't break the build before a demo...). Whatever, there's
no doubt there will be changes one day. There are syntax-related
issues with 1.1, but as 
<a href="http://dehora.net/journal/">Bill deHora</a> put it (in a
different context): 
"If there's a 
Maslow hierarchy of needs for the Web,
syntax is on the bottom.". As far as I'm concerned the big
question is whether (maximal) logical compatibility is maintained
with the existing layers of the Semantic Web stack, i.e. RDF and
OWL.

 Do what you like, just don't hurt the triples.

Some sentences, especially in earlier drafts of 1.1, seemed to
suggest the distance from RDF was such that interoperability would
be a non-starter. (It's worth bearing in mind that the requirements
of the OWL/Description Logics community don't necessarily coincide
with those of the (Semantic) Web community at large). I've barely
started getting my head around the new material, it will be a good
while before I'll have any hope of judging this for myself. I
really am not a logician.

<a href="http://www.cs.man.ac.uk/~horrocks/">Ian Horrocks</a>, who 
is, just posted the 
<a href="http://lists.w3.org/Archives/Public/public-owl-dev/2006OctDec/0033.html">following</a>
to the public-owl-dev@w3.org list:
<blockquote>The current status is that OWL 1.1 has a triple syntax
that is fully backwards compatible with OWL: any OWL DL ontology is
an OWL 1.1 ontology. There are a couple of new features of OWL 1.1
that we were having trouble figuring out how to serialise as
triples, but after discussions at ISWC and the OWLED workshop
(thanks to Alan Ruttenberg for some helpful suggestions) we now
have a solution, and a revision of the triple syntax that covers
all of OWL 1.1 will soon be available. Regarding the semantics, it
may not be possible to extend OWL's RDF-Compatible Model-Theoretic
Semantics so as to *completely* capture the meaning of OWL 1.1
while at the same time giving *all* the triples their basic RDF
meaning as facts. Due to the backwards compatibility of the syntax,
however, the meaning of the OWL part of OWL 1.1 will be captured by
the existing RDF-Compatible Semantics, and interest has been
expressed in trying to extend this (the existing RDF-Compatible
Semantics) so as to capture at least some of the meaning of the OWL
1.1 extensions.</blockquote>

 (I'm still not 100% clear - I take that as saying not every
 OWL 1.1 ontology/conclusion is a valid OWL Full
 ontology/conclusion just yet, but it's getting closer...)

It seems almost self-evident that when major changes to existing
specifications and/or entirely new Web specifications are proposed,
the onus should be on the proposers to clearly demonstrate they
won't break the Web (
<a href="http://www.imdb.com/title/tt0072431/quotes">else</a>: "
A riot is an ungly thing... undt, I tink, that it is chust
about time ve had vun."). In this particular case, the work
mentioned above sounds like it goes a long way to fulfilling that
criterion. Looks to me like cause for (cautious) optimism.

See also: recent posts 
(and comments ;-) at 
<a href="http://clarkparsia.com/weblog/">Tales of a Semantic Web
Consultancy</a>; plus 
<a href="http://www.cs.man.ac.uk/~horrocks/Publications/download/2003/HoPH03a.pdf">From
SHIQ and RDF to OWL: The Making of a Web Ontology Language</a>
(pdf); 
<a href="http://www.cs.man.ac.uk/~horrocks/Publications/download/2006/HoKS06a.pdf">The
even more irresistible 
SROIQ</a> (pdf).
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