Here in Austria, we had a rather problematic court ruling regarding this. Following to this and to common recommendations catch-all domains were mostly disabled, at least, you run them at your own risk.
What it was about: Say, there was a review or best-price-search site (here, "service.at"), using catch-all and mapping subdomain requests to product searches. So "acme.service.at" would be remapped to, say, "service.at/search?q=acme". Now Acme sued, claiming anything containing the name "acme" on the web ought to point to their site, including the subdomain "acme.search.at", since they were the owner of the name "Acme". To almost everybody's surprise the court decided that this was true, according to naming rights, and that a subdomain containing this name, even if just implemented virtually by a catch-all mechanism, was an infringement. This also implies that "acme.example.at", which is included in the set of "*.example.at", mapped to the very same as just "example.at" is a possible infringement. – Strange, but this is as it is. And, yes, it's particularly about search engines, like Google.
(I really don't remember the particulars, since this has been some years ago by now, but we may assume that the results returned by the service weren't exactly favorable and that the particular search enjoyed a higher Page rank than the site of this vendor, or at least a rank, which brought it up near the site of the vendor in search results.)
IANAL, and I'm just speculating here, but the law could have been termed as "copyright laws apply to domain names on the internet" (i.e you can't use the name of a brand you don't own in a domain name), and acme.service.at is a domain name, but service.at/search?q=acme is not.
What it was about: Say, there was a review or best-price-search site (here, "service.at"), using catch-all and mapping subdomain requests to product searches. So "acme.service.at" would be remapped to, say, "service.at/search?q=acme". Now Acme sued, claiming anything containing the name "acme" on the web ought to point to their site, including the subdomain "acme.search.at", since they were the owner of the name "Acme". To almost everybody's surprise the court decided that this was true, according to naming rights, and that a subdomain containing this name, even if just implemented virtually by a catch-all mechanism, was an infringement. This also implies that "acme.example.at", which is included in the set of "*.example.at", mapped to the very same as just "example.at" is a possible infringement. – Strange, but this is as it is. And, yes, it's particularly about search engines, like Google.
(I really don't remember the particulars, since this has been some years ago by now, but we may assume that the results returned by the service weren't exactly favorable and that the particular search enjoyed a higher Page rank than the site of this vendor, or at least a rank, which brought it up near the site of the vendor in search results.)