Maqetta is a "What-you-see-is-what-you-get" HTML 5 Editor by IBM. The software itself is entirely written in HTML and runs in a webbrowser window. It uses Dojo for the interface itself. Maqetta is an open source project hosted at the Dojo Foundation and supports some Dojo widgets. Basically it's for creating some quick basic layouts with HTML and DOJO.
I did a first glimpse into this product and it seems to be a nice Drag-and-Drop utility for this basic tasks. More interesting is the point that a WYSISWG editor runs in the webbrowser for creating webbrowser applications. This could be a nice concept for the future development of HTML applications, especially with the usage of JS-APIs. It also shows the capabilities of Dojo based webpages, because Maqetta itself has a nice and usable layout.
There is no Esri plugin (yet), but for playing with HTML 5 and Dojo it should be a nice thing. Maybe it fits into the space between the template-downloader-user and the "i-write-everything-myself" user.
Best regards, Axel
P.S.: If I wrote the name of the software wrong (Maquetta, Marquetta, Marqetta, Marge-TTY), please keep the typos. 😉