select by streak

Lets say I have a table like this:

id int  <== primary key
ts timestamp 
name text
status char

status is G for good or B for bad.  How do I do something like:
SELECT name FROM mytable WHERE <last 3 entires in a row have status =
'B'> and <has been no good ones in the past week> ?

-- 
Joseph Shraibman
jks@selectacast.net
Increase signal to noise ratio.  http://www.targabot.com