Certain subtle trends in fashion this year, I think, can be traced back to the AMC original series. So many of the trends in dresses have been belted, pleated and looked so similar to Peggy Olson's day-to-day threads (except now in 2009 they're in Technicolor!) I can even see a subtle link to Mad Men in the shirt dress trend, as well as the more frequent use of plaid.
As far as men's fashion I've noticed that many men have started to ditch the sports jacket for the tailored vest when looking to dress to impress. Also, I just recently learned that Banana Republic has partnered with Mad Men to create a line of suits. ME-OW. This trend excites me a great deal, mainly because I like my men like I like my Draper: dapper.