The first stable version supporting Seaside will be 3.1.

The first release candidate, 3.0a, was released on March 7th 2008.

First, make sure the NetClients package is loaded. You can use this Smalltalk code:

PackageLoader fileInPackage: 'NetClients'

Alternatively, you can create a separate image that preloads the package (that's explained in another FAQ).

Once you have the package loaded, you can open a FileStream on a remote URL just like you would do for a local file:

(FileStream open: 'http://www.gnu.org/' mode: FileStream read) contents

A continuation object contains a snapshot of the program execution including all the local variables, and allows to restore the execution of the program from where the object was created. GNU Smalltalk supports continuations.

You will probably never use continuations directly, but they enable doing very interesting things, such as generators and continuation-based web frameworks.

GNU Smalltalk uses preemptive green (non-native) threads; that is, multiple Smalltalk processes are run by the virtual machine in one operating system thread. The main disadvantage to this approach is that it is impossible to use multiple CPUs even when the machine has them available; for single-processor CPUs, green threads are faster than operating system threads, because they make context switches cheaper.

Not yet, though there is a minimal debugger example included in the examples, as well as support for debugging in the VM.