The following are some notes on getting the Creating a Windows SharePoint Services 3.0 Web Part Using Visual Studio 2005 Extensions of the SDK to work.
No SharePoint Site exists at the specified URL
In the Visual Studio Project Properties, the Debug section contains a setting: Start browser with URL. This needs to reference the sharepoint site. For instance if your sharepoint site is on the Euclid box at port 8080, then it will need to be set to http://Euclid:8080/.
Otherwise the error will be reported durnig deployment as: No SharePoint Site exists at the specified URL.
Enabling ASP.Net Debugging
The debug attribute for compilation needs to be set to true in order for debugging of the web parts from within Visual Studio. If the option is not set, the deploy will succeed but a browser will not be launched and attached to Visual Studio.
<compilation batch="false" debug="true">
Web Part not showing in Miscellaneous section
If after you have deployed to your Sharepoint Site and you are not able to add the newly deployed web part, make sure you have deployed it to the correct site. In my case, I was not able to view it in the Miscellaneous section. Fortunately I found a helpful post: http://www.developer.com/net/asp/article.php/10917_3620316_1
Tue, Feb 19 2008 12:20 PM