Thanks again for this great plugin and please take my observations as a desire to help improve it.
Sometimes (randomly, I cannot fix the reason) the share buttons dissappear. For ixample, in http://somos.vicencianos.org/blog/2012/12/26/siete-desafios-para-el-ano-de-la-fe/ you can see the image with the word "Share" is there, but no button appears. But. in the same blog in other posts the plugin shows well, for example in http://somos.vicencianos.org/blog/2012/12/26/orientalium-ecclesiarum/
I cannot guess the reason.