Firefox 3.0 will not be officially supported by Mozilla for much longer and some planned KeeFox features will be easier to implement if I concentrate on version 3.5+ only. For these reasons, KeeFox version 0.8 will require Firefox 3.5+.
I don’t plan to drop support for 3.5 until after the release of KeeFox version 1.0 unless Mozilla officially withdraws support in the mean-time. However, to ensure you’re getting the fastest and most secure browsing experience, it is always advisable to upgrade to the latest Firefox version as soon as possible.

I assume when you say: “I don’t plan to drop support for 3.5 until after the release of KeeFox version 1.0 unless Mozilla officially withdraws support in the mean-time.”
You really mean: “…drop support for 3.0…”
To clarify and update: When I said 3.5 support will not be dropped until “after the release of 1.0 unless Mozilla officially withdraws support” I was referring to 3.5; 3.0 support has already ended. Additionally, I’ve learnt that Mozilla intend to remove support for 3.5 in less than 6 months which is likely to be before version 1.0 of KeeFox is officially released. I won’t guarantee support for 3.5 beyond Mozilla’s end of support but I don’t actually intend to make any changes that will break 3.5 support before KeeFox 1.0 is released – I’ll announce the exact supported versions nearer the time.