Thanks to @bmann I came across a really great post from Morten Just on using the new Google Draw for wireframing, (and @chrisstrahl for reminding me to post this up to the group). He's created a bunch of templates and stencils and shared them publicly so anyone can use them. I have been trying it out for a set of wireframes I've been working on this week, and it's actually pretty good. I've been using Mockingbird (http://gomockingbird.com) a lot lately, and I'm not sure if I've been swayed one way or the other quite yet, but if people keep sharing templates on the GDraw, we could end up with quite the library of templates.
The post with links to the shared templates is here: http://mortenjust.com/2010/04/19/a-wireframe-kit-for-google-drawings/