Hasslewise: I was traveling with my partner, she had to wear the hijab (hair covering) at all times while outdoors which was a bit of a challenge (try keeping it on with the wind blowing out of the metro in Tehran!). People are very accommodating though, a huddle of women would sometimes form around her to set things right if it was slipping off! This was exacerbated by the time of year (midsummer), you'd be better going sometime cooler. Only other thing I can think of is that the banking system is totally cut off from outside (no ATMs which accept foreign cards, very few places accept western credit cards), so you need to carry in as much cash as you need for the trip. Definitely intending to go back in the future with more time on our hands - there's just endless places to see and visit - it truly was a unique experience.
We've got some blog posts here that might help: http://www.sarahandniall.com/2011/08/iran.html http://www.sarahandniall.com/2011/09/traveling-as-woman-in-i... (I have blog posts written but not published for the rest of the trip - really must get them up!).