Why don't Muslims shake hands with the opposite gender?

Just as many people harangue "nothing is too trivial for the mullahs to pontificate/legislate over"...the converse is often true too...the most ordinary acts of Muslims are automatically imbued with "what-a-weirdo"undertones and unpleasant implications.

An opinion piece in a prominent Australian newspaper (incidentally by a Muslim) analyses the propensity of an increasing number of Muslims to refuse/shy away from shaking hands with the opposite gender...

"a small but growing number of young Australian Muslims identifying more with the intricacies of their religious beliefs, it is unacceptable to touch a member of the opposite sex to whom they are not related. Not only is pecking the opposite sex on the cheek a no-go to avoid temptation, even shaking hands is taboo. This extends to non-Muslims they come into contact with.
Recently I have been caught out several times on this issue in public. On each occasion I was left feeling awkward, if not a little embarrassed. By the time I had figured out that the man did not shake hands, it was too late: my hand was left hanging in the wind.
It was hard not to take this personally, even though for Muslims who take this position it is nothing personal at all. They simply do not want to shake hands because they believe it is against their religion. To avoid seeming disrespectful, these men will often touch their heart as a sign of goodwill."

[...]

"But this issue is not restricted to Muslims: Orthodox Jews do not shake hands with the opposite sex. Nor should it be assumed that only Muslim men take a strict approach, as some women take this position even when their husbands ignore it."

link: Austrolabe (don't miss the lively comments section!)