Owners of the retail edition of Counter-Strike have noticed some oddities with the version 1.1 patch that was released earlier today (story). We contacted Valve, and they informed us that the reason the retail patch does not include the new de_dust2 map that's in the mod release, is because there are certain maps they don't have the rights to use at retail. Therefore retail CS users will have to download the map when they connect to a server for the first time. Here's what Valve told us about the error message that some users saw regarding an incorrect version number:

There are three master servers you can potentially (determined randomly) attempt to get a server list from. If your version number is incorrect when you try to connect to one of these, it triggers the update system.

One of the three master servers was not upgraded yet, so this was tripping some people up. This is fixed now.

Update: cliffe of the Counter-Strike team sends words that they are working on an "unofficial mappack" that will offer the aforementioned missing maps to owners of the retail edition of Counter-Strike. It is expected to be released tomorrow.