Andy_Langton - 12:22 am on Jun 8, 2012 (gmt 0)
If a site dose not display contact info it looks like its hiding something, which it probably is.
But this is just blanket advice, and that does not a ranking factor make.
Does Amazon display a phone number? Ebay? HP? Microsoft?
Yes, customers want a phone number, and it is good practice to display one - but it's a big leap to say that displaying one affects Google ranking directly.