Investors aren't warming to Salesforce.com's (CRM - News) rumored plan to buy social media marketing firm Buddy Media for $800 mil. Salesforce shares fell 3.3%. Buddy helps companies manage ad programs on social media sites such as Facebook (FB - News). It would be the latest in a land grab in social media marketing. Oracle (ORCL - News) last week bought social media marketer Virtue for $300 mil, and Adobe Systems (ADBE - News) picked up a company in the sector earlier this year.