Last night I got an e-mail by palm, that following-up to my request, the source code releases for the WebOS 1.1.2 and 1.1.3 releases have been uploaded to opensource.palm.com.
I think the response time was very quick, and I thank them for that. However, still sad that one has to remind them of it. Let's hope with future releases they have a fully automatic process for that.
Just to be very clear: The GPL does not state that you have to automatically have the source code on a web site. But the way how Palm's written offer is phrased, they say that you should visit the website to download the sources. In that case, the web site of course needs to contain the sources...
Additionally they also offer the source code on a storage medium, if you write them snail mail to a specific address - which is a good safeguard since the GPL says it has to be made available on a storage medium commonly used for software interchange.