Basic Navigation
Up/Down arrows use to navigate messages.
Tab/Shift-tab same as Up/Down arrows (outside edit mode)
Home/End focus first/last message
Space go to next unread message.
Left/Right arrows to switch focus between digest panel and wave panel.
Page Up/Down go to the next page in the panel [does not currently work, known bugs]
Ctrl-Space mark all messages read (focus must be on wave panel though)
Managing your Messages !
Enter replies to messages: the new message will appear just below the selected message (it will be the same indentation level if it is the first reply, but indented more if a non-first reply).
Shift-Enter replies to messages at the end of thread: the new message will appear at the same indentation level, and at the BOTTOM most position.
Shift-Enter while editing ends editing (equivalent to clicking the done button)
highlight text + Enter inline reply: the new message will appear indented and INSIDE the current message.
Ctrl-R same as enter
Ctrl-E edit message
Ctrl-Enter (while editing) insert inline reply at caret
Editing Made Easy !
Ctrl-B toggles bold attributes for selected text
Ctrl-I toggles italics attributes for selected text
Ctrl-G Color
Ctrl-L Links to another Wave (highlight text, hit CTRL-L and put in a URL or a Wave ID (see Debug menu for ID’s) [NOTE: we will soon change the key combo]
Copy and Paste
Ctrl-C copy the selected text.
Ctrl-X cut the selected text.
Ctrl-V paste the text from the text buffer.
Formatting is Fun !
Ctrl- Make the current line a heading, where n = 1..4 for different sized headings.
Ctrl-5 Bullets
Ctrl-6 Normal (removes heading/bullet style, but not bold/italic etc. current visual glitch in some browsers where text stays big – but this is not persistent.)
Ctrl-7 LTR + Left align
Ctrl-8 RTL + Right align

Delete a message in a thread
Is there a keyboard shortcut for this? Or even to navigate to the drop down menu within a message? Or to choose any of those options without using the mouse to pull down the menu?
Just hit Esc
if it's a new reply that you've just created and are editing for the first time, you can just hit Escape "Esc" and it will delete that reply. I haven't found one for deleting an pre-existing blip or getting into the drop down menu
shortcut for the blip OK button?
Is there a keyboard shortcut for ending a blip? I type a blip and hit return, expecting it to act like IM, which of course it doesn't. I'm still in the blip and have to grab my mouse to click the ok button. Sure would like to know if there's a shortcut for the blip OK button.
It's Shift+Enter
It's Shift+Enter
Yeah, anytime you're in edit
Yeah, anytime you're in edit mode, pressing "Shift+Enter" is the same as clicking the "Done" button.