Think that MI5 and the other intelligence/security agencies need some congratulations for this. Assuming they have foiled the plot (and I pray that they have), that is a great piece of work. As you say, you cannot deter terrorists with punishments... you have to prevent them from doing it in the first place.
Re tampons, aircract ones probably don't work too well (unlike t-shirts, one size does not fit all...

). However Tampax Compact are really quite small, discreet and packaged in a pretty way. I honestly don't think that there is anything to be embarrassed about having your period - having a period is a fact of life and we wouldn't be able to reproduce if we didn't
Like others, "valuables" are my only concern - laptops, cameras, i-pod, jewellery. It sounds as though, from what Obi said, the airlines are doing their best to check these in seperately. If this turns into a longer term thing, hopefully airlines and insurance companies will come up with an official line on this (to help make packing and/or deciding what to leave at home easier...).
The secondary screening makes sense. They did that (and maybe still do) in Australia after the Bali bombings. When I went through, they did a really quite thorough search of everyone's hand luggage just before entering the gate. You do have to allow extra time to get onto the plane...
Am just so glad to be reading news of cancellations, delays and new security measures... and NOT of plane crashes and death.
Hope that the airlines are able to look after people stranded away from home.
Best Wishes,
Boo