Absolutely, though only a few at this moment.
|⌘ + N||Bring up the new tweet window.|
|⌘ + Enter||Post from current new tweet window.|
|Esc, H, or Left-Arrow||Dismiss current new tweet window, or go back to previous view.|
|L, or Right-Arrow||Show the thread or author profile of currently focused tweet.|
|J, or Down-Arrow||Move down by one tweet.|
|K, or Up-Arrow||Move up by one tweet.|
|Shift + Space||Page up.|
If it is an essential feature (such as those already in Twitter.app), then most likely it is already somewhere on my todo list to be implemented.