In one 2 measure phrase of 4/4 time, beat 1, the "and" of beat 2, and beat 4 in the first measure, beat 2 and the "and" of beat three in the second measure  is one of more common used clave rhythms. Often heard in bossa novas, like " The Girl from Impanema".

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Clave means Key or code in spanish. In Afro-cuban or salsa music it is as fundamental to that music as swing in jazz. It is the KEY to that music. 

There are several basic types of the Clave:

The most common is "son" clave: 

Another common feel is Rumba Clave:

Clave feels come in either 3-2 or 2-3 flavors. ie beginning with 3 notes in the first bar and 2 (3 2) in the second, or the reverse....2 in the first and 3 (2 3) in the second.

This is a Son Clave in 2-3

Brazilian Bossa Nova and samba also uses a type of clave feel that can come in both 2-3, and 3-2.

a Brazilian Clave might be like this:

Sometimes in a song the Clave will reverse, starting with 3-2, and changing to a 2-3....

It's something you really need to listen to inorder to get the groove.....

This is a pretty good explanation:

http://musiclessons.com/youtube/share.cfm?v=eel1mqQrJIQ&t=clave

http://musiclessons.com/youtube/share.cfm?v=U8W9E1xgNaw&t=clave

Thanks for the notation! Here's a pretty decent video that explains it too:

http://www.youtube.com/watch?v=0-tm497rXF4

What is the orgin of this rhythm?