This is very good news. The OpenInkPot firmware on a Hanlin V3 also supports a recent version of FBReader. I don't have a complete set of screenshots (scans), but see
20090222 snapshot for a short tour of the many FBReader options available in OIP.
One thing this will do is reduce the need to convert to a "preferred" format, such as FB2. There are some differences between formats, but FBReader by and large treats all formats similarly. Note that it only supports single-file HTML, which can be zipped if the HTML references images.
If you want to try it out,
FBReader is available for Windows and Linux Desktops (and there is an unsupported Mac version).