Having lot of web 2.0 profiles doesn't matters with Google updates, But the post should be unique and readable for users. With the recent penguin update, Google has released 2 lists (winners / losers). Some of the sites like digg.com, nextag.com, etc.., were came under losers list, So placing links on those sites will lose its visibility in Google. You must aware of placing links in web 2.0 sites.