Out of sheer curiosity, and because quite a few users have asked me about cross-browser compatibility, I took one of the websites showcased on the Adobe Muse site (which, by the way, was entirely created using Muse) for a spin over at Adobe BrowserLab, and here are the results.
With BrowserLab you can preview how your web pages will display across browsers and operating systems.
One of the promises of Muse is that "Muse creates cross-browser compatible code for you, so you can focus on your design and we’ll make sure your site looks great". Well except for IE 6.0 on Windows (which does not display transparency in PNGs) and a couple of browsers not honoring the left padding of the page, I'd say that all looks pretty good.
This is a very superficial test, I'll try to create a more thorough one in the near future.