As we're now in RC for Fennec 1.0, some focus on website compatibility is ideal. A test guide has been created on the QA/Fennec Wiki, so for those that are currently testing on the n810 and n900 (as well as desktop builds of course), take some time out and do some our your daily browsing on Fennec. Even if you already do this, try experimenting a little and check out some sites and “things to do” mentioned in the test guide.
Info about RC (including download links under “Downloading”): https://www.mozilla.com/en-US/mobile/1.0/releasenotes/
Test Guide: https://wiki.mozilla.org/QA/Fennec/Daily_Browsing
If you have any questions or concerns (or if you feel like something is missing), please feel free to bring them up!