In the last six months since I analysed Mendeley's contribution to Computer Science OA in June 2011, they appear to have increased their membership of that community by 37% and the ratio of full text documents to community members has increased from 0.66 to 0.71. The number of OA documents has increased by 47% to 11,757 and the number of OA active users (i.e. users who have made at least one document public through Mendeley's servers) has risen by 46% to 2,441 but still represents only 15% of the total membership of that community.
Congratulations to Mendeley - their service is obviously rising in popularity and hence in significance to the community. OA analysts will note that the increase in open access documents comes from increased membership, rather than a change in behaviour of the community.