Via SERoundtable I got a heads up on something going wrong with Google results for its own sites. If you search (for instance) for Google Ireland, you'll actually get google.nz (Google New Zealand) as the top result. I tested 162 regional Google sites for their ranking and, shockingly, in 61% of cases Google was unable to return the correct regional site in its own results.
As well as very poor results for searches like "Google [country]", you'll get the same mismatch if you search for the actual domain. This is what would usually be deemed a "navigational" search query - i.e. one with a very clear most relevant result. If you search Google for "example.com" then you should rightly be expected to be sent to somewhere on example.com. Search engines should rarely (if ever) get navigational queries wrong.
Google have done some "interesting" things with their handling of regional searches and with their handling of certain types of duplication. I think they've been hit pretty hard by their own changes, and they performed very poorly for this selection of navigational queries. But let's not mess around. What we need is pie charts ;)
Ouch. It's a sorry tale here. In almost 2/3 of cases Google does not return the correct site. For some unfortunate Google regions the results are even further from the mark. Saint Vincent is beaten out of results by Google ventures, and Andorra loses out to Adsense.
So what exactly is Google matching instead of the right site?
All in all, a bit of a tale of woe. I'd hate to be Google's SEO agency at this point ;)
In case you want the full set of data collected, it's in the Excel spreadsheet attached below.
Hat tip to blackdog for the spreadsheet of regional Googles.