Is Loudmouth XMPP-compliant
Starting with Loudmouth 1.4.0 Loudmouth is now XMPP 1.0 compliant.

Does Loudmouth work on Windows
Yes, it has been reported that Loudmouth successfully work on Windows. Look in the README.WIN32 file for more information.

Why the dependency on GLib
For two reasons actually, it provides a platform independency layer making it easier to port it to other platforms than the original Linux platform. However more importantly it provides a lot of data types and utility functions that makes developing quicker and more stable.

Is TLS/SASL supported
Starting with Loudmouth 1.4.0 TLS and SASL are both supported. The old SSL v2 mechanism is also supported.

Can I write Jabberd components with Loudmouth
Not at this moment but adding support for that shouldn't be too difficult. The best way to help if this is something you need is to join the Loudmouth mailinglist and help defining what needs to be done.

Are there any bindings available
The only bindings currently available are Ruby bindings that can be found on the download page.