Unfortunately, Arsenal's rather excellent bid of £40,000,001 was not enough to get Liverpool to condone the sale of Luis Suarez, but, according to the Guardian, it has activated a clause whereby Liverpool must allow Suarez to open talks with Arsenal if he wants to. Obviously, that means he can legally agree personal terms with Arsenal (and I'm sure they already have a very, very good idea of what he wants), and that can put pressure on Liverpool, especially if he puts in a transfer request.
That doesn't mean Liverpool will sell Suarez, though; they could be waiting for an offer for Suarez from abroad (such as Real Madrid) or could be holding out, as they indicated earlier, for a higher fee, in an effort to drive Arsenal away. For that reason, Arsenal are wondering if the clause Suarez has in his contract is actually a release clause:
Arsenal have evidently been encouraged to believe that £40m-plus is a sale clause and a legal dispute over the wording of Suárez's contract cannot be discounted
PDB EDIT (4.15PM): The Guardian's article about the bid contains this, which might clear up the whole "clause thin