Selling locally hosted versions is absolutely 'conveying' and the GPL's text is quite clear.
Selling the rights to the software or the company itself is straightforward -- just because it's licensed under the GPL doesn't mean the company doesn't own the copyright! The GPL text is intentionally unclear about this, as the FSF pretends that everyone is going to assign copyright to them for 'safekeeping'.
Granted, selling the software outright would be conveying, but what if the company leases their service on a remotely administered box colocated in a local data center? I think it is not totally clear that software has been conveyed, especially if it is under GPL2.
Regarding selling rights: you perhaps misinterpreted the scenario I am proposing. I am supposing that a company has written a proprietary "cloud" internet application that incorporates Zed's GPLed Lamson component -- which you say they can do because no software is conveyed. However, if they want to sell their software or (potentially) their company, I am saying that -- cloud or not -- they will be interested in acquiring a non-GPL license from Zed because the sale of their non-GPL software without such a license may run afoul of the GPL... which is why Zed's use of the GPL is relevant even in a "cloud" context.
Selling the rights to the software or the company itself is straightforward -- just because it's licensed under the GPL doesn't mean the company doesn't own the copyright! The GPL text is intentionally unclear about this, as the FSF pretends that everyone is going to assign copyright to them for 'safekeeping'.