So http://devwiki.electricimp.com/doku.php?id=ledcodes documents the LED codes.
The fast/slow/very slow thing is a bit hard to gauge. Plus, Im a kinda color blind.
What about a different scheme, which uses an unambiguous pulse to mark the beginning of a code followed by a certain number of flashes (all of the same rate, so no slow/very slow/fast thing). The a 2 second delay before another one, so there is no issue of one running into another (I was getting the 3 green then 12 red and thinking that was some undocumented sequence).
Long red, followed by 1 red flash = Failed to receive command from Blinkup
Long red, followed by 2 red flash = Attempting to join WiFi
Long red, followed by 3 red flash = Connection lost, attempting to reconnect
Long green, followed by 1 green flash = Successfully received command from Blinkup
Long green, followed by 2 green flash = Connected to the cloud (discontinues after 60 seconds)
This also has the benefit of allowing you to add more codes in the future, just add one more flash to the a sequence