I have only skimmed read this thread so probably everything I am going to say has already been said, and better, but, fwiw...
there is a huge difference between an afghan style burqa and a head scarf- and as far as i can tell from my observation of women in London there are about 100 different gradations in between. I have only ever seen a handful of women with complete covering in the West (including gloves, and in a handful occasion, a sort of metallic face mask which i believe is saudi or yemeni custom? someone will know better!).
As far as I can tell, wearing a headscarf and/or modest clothing is a religious/cultural thing for the majority of Muslim women. I used to live in Kilburn where there is a huge Somali and middle eastern population. my gp wore a heascarf and an overcoat; the lovely nurse at the contraception clinic wore a headscarf and conservative clothing; and lots and lots of girls and women (including at work) wore the heascarf- sometimes coupled with traditional clothing, other times with jeans or office wear.
I mention these examples not because i find it so exceptional that a muslim woman can be a doctor (before someone comes out and accuses me of that!) but because i simply do not believe the simplistic equation islamic clothing= women oppression. That's just ignorant white men talking, as far as I am concerned. Of course there is oppression and ignorance etc in certain segments of society, but then address the causes of it, rather than a superficial way to visually "integrate" people.
It is however a way to "wear your faith", and as such I can see that it grates on our increasingly atheist society. We just do not like to be confronted with religion, either spiritual or cultural, because we don't understnd it anymore, and therefore we are scared of it.
covering your head is not exclusive to muslim women: orthodox jewish women do it too, and until recently it was commonplace in catholicism too- nuns still do it.
The burqa, on the other hand, is harder for me to accept. I think at that point you do enter the realms of diminishing women and it saddens me and shocks me that it is considered necessary in certain cultures.
sorry- very rambly post and largely uninformed that adds nothing to the debate, but i couldn't resist possibly