It's not quite Microsoft / Yahoo! but it's the largest acquisition of a web company in some time. CBS announced Thursday that it would pay $11.50 a share in an all-cash tender offer for CNET. The deal is worth $1.8 billion and vaults the company forward in it's vision of becoming a bigger Web player. "There are very few opportunities to acquire a profitable, growing, well-managed Internet company like CNET Networks," CBS Chief Executive Leslie Moonves said in an interview. The deal is expected to be completed in the third quarter of this year. The LA Times has more here.