willybfriendly - 10:41 pm on Feb 11, 2010 (gmt 0)
In my case, switching from a hyphenated URL to the non-hyphenated version it took just about 3 months for traffic to show a significant recovery.
Unfortunately, neither Yahoo or Bing seem to handle the 301's as well as Google, and rankings on key terms has never been recovered in those SE's.
It is a risky move, but again, in our case the hyphen gave every sign of being a liability that we could not overcome, even though the domain had been in use since 1999. Very few hyphenated domains rank top 10 these days - another example of using a blunt instrument to clean up the SERPs in my opinion.