TeamCity plugins - triggering events on build tagging

I've not yet fully looked at the OpenAPI for TeamCity so I'm not sure
what is or isn't exposed just yet, but I was wondering if I could
respond to a user adding a tag to a build?

The workflow I want to create is:

• User tags a build with "qabuild", which triggers my plugin to:

• Create a deployment ticket in JIRA

• Create a "please test" ticket in JIRA

• Update confluence wiki with deployment references

All the later jira/confluence interaction is easy so all I need is the
hook into tagging builds.

I assume I'd need a Server Extension
(http://www.jetbrains.net/confluence/display/TCD3/ServerSideExtensions)
but there doesn't seem to be any extension points relevant to what I want.

I'm looking at doing this for the Benares builds...

Anyone know if I can, or can't do this?

Mark