Recent economic crisis had its implications on the way women behave and look these days. In order to "fight" for their jobs, women tend to behave more aggressively, look more masculine, and prefer "menswear" for work.
It may work on subconscious level too - "if you wear pants, your paycheck is bigger".
Men-style dressing goes back to the 1930s when Katharine Hepburn and Marlene Dietrich became symbols of masculine glamour in tailored suits and ties.
Take any women celebrities and photoshop them as men. Give them men's hairstyles, men's clothes, beards and mustache, etc.
Here's a good example by allanpanisa.
This gallery only contains our top 68 selections from its parent contest Men!. All 70 contest pictures can be viewed here.