To answer your question, I haven't heard any yet this year.
But I got curious and did a little research, and aparently there are 2 different types of cicadas here in Missouri.
There are the Dog Day Cicadas, and they generally come back every year. They're the ones I remember hearing as a kid. Their "song" has varied notes, from high to low.
The Periodical Cicadas are the ones that come every 13 years or 17 years. Their "song" has less varied notes, so they make a more constant noise (like the ones in the video). 2011 does happen to be a year for the 13 year cicada here in Eastern Missouri. Judging from what I've read, we'll likely start seeing and hearing them in late June to early July.
LOL sorry for all of the info. I was just curious about it.