Well, I have continued my quest for resolvable, RDF-producing GUIDs for taxon/name-related stuff. I have gotten a lot of good information from reading Rod Page's BMC Bioinformatics paper (http://dx.doi.org/10.1186/1471-2105-10-S14-S5) and from investigating his http://bioguid.info/ site.
From the standpoint of the "sec./sensu" part of a TNU/taxon concept, based on the recent discussion, it sounds like the DIO solution for publications is a good direction to go IF resolution services producing RDF comes into existence and IF it becomes possible to actually search for the DIOs of more obscure publications. I tried using Rod's site to look up a journal article using the ISSN, volume, and page and the web interface found the DOI and generated RDF just fine. However, an attempt to use the web to find the DIO of Gleason and Cronquist's Manual of vascular plants of Northeastern United States and adjacent Canada failed despite a half hour of effort (I found the UPC, the LOC call number, and the ISBN, but no DOI). Maybe there just isn't a DOI for it but there should be a way for me to know that. So DOIs for books and old journal articles are not really ready for prime time.
From the standpoint of the "scientific name" part of a TNU/taxon concept, I had better luck (sort of). Rod's "Status of biodiversity services" page (http://www.bioguid.info/status/) was really cool. I saw resources I hadn't known about before. I tried out several of the services that claimed to issue LSIDs.
Catalog of Life's LSIDs didn't work with either the http://www.bioguid.info/ or http://lsid.tdwg.org/ proxies with either a web browser or the OpenLink RDF browser. I only got an empty RDF element in response.
Index Fungorum was down.
IPNI seemed to work. However, I was somewhat appalled to observe that they seem to change the revision identifier any time that they change any part of the metadata. That renders the LSID useless as a permanent GUID for the name and I believe is inconsistent with the design of LSIDs where the revision is only supposed to change if the underlying data itself (NOT metadata) changes. (Catalog of Life says that they change the revision identifier EACH YEAR for all of their records! That's even worse!) If I'm remembering the TDWG LSID recommendations, it is not even recommended to use the revision part of an LSID at all in the biodiversity informatics context.
ubio.org's LSIDs seemed to work properly.
[sorry - didn't try zoobank since I was looking for plants]
I don't know which (if any) of the Web sites listed on Rod's status page use generic HTTP URI guids (rather than LSIDs) to refer to taxon names. I tried out the Global Names index that Pete was mentioning. The URI version of the UUIDs (e.g. http://gni.globalnames.org/name_strings/3a70f04d-fd29-5570-ba91-52dae0c3d07f) do resolve under content negotiation, but the only useful information that the RDF representation seems to provide is the actual name string that was used to generate the UUID. Until some other useful linked information is added to the RDF, there doesn't seem to be much advantage in pointing a semantic client to the URI over just using a string literal for the name.
So the bottom line is that of the LSID services for names that I've tried so far, only ubio.org seems to have LSIDs for names that are unchanging, can work as a proxied URI, and that produce actual useful RDF. That's pretty disappointing given the apparently huge amount of work that's been put into building these various systems.
Steve