The Mariners have shown "signs of interest" in Jose Guillen according to Bob Dutton of The Kansas City Star, but exactly just how much interest is tough to gauge. Royals' officials indicated that they have yet to receive a formal inquiry.
Guillen, 34 this month, is having a resurgent year with the bat. He's hitting .275/.318/.542 with eight doubles and eight homers in 129 plate appearances, though he's almost exclusively a DH nowadays. This season is the final one on his contract, which is putting $12MM in his pockets this summer.
The Mariners have made no secret about their desire to add offense, especially since their DH spot has been a non-factor - just a .189/.250/.207 batting line with just two extra base hits (both doubles). Mike Sweeney (.172/.273/.172) and Ken Griffey Jr. (216/.266/.243) have been the main culprits. For comparison's sake, NL pitchers are hitting .164/.205/.202, less than a 40 point difference in OPS.
Kansas City would assuredly have to eat some money to make a deal happen, and generally speaking, the more money a team eats, the more they get in return. They've been said to be looking for any kind of pitching, just like everyone else.