As Matthew already noted, the Mariners have declined their 2011 options on Erik Bedard, Russell Branyan, and Jose Lopez. The first two have thus become free agents, while Lopez has become nothing, nothing at all, despite all of the promise and all of the skills. He remains under team control and could settle for a mild raise from his 2010 salary, but this is likely the first step on the path towards seeing him disappear.
Please do note the use of 'likely' over 'definitely', though. Nothing is guaranteed, and there are reasons the team might want Lopez back. Take nothing for granted.
Anyway, that isn't all that happened. Via Matt Pitman, we learn that Ryan Langerhans and Guillermo Quiroz have become free agents, and from Mike Curto, we learn that Ryan Feierabend, Chris Seddon, and Sean White have been outrighted and may become free agents as well. Any of these players could come back and play in Tacoma, but any of them could not, too, and none of them would represent any sort of loss.
Langerhans, of course, we like, but he doesn't have much of a place. Quiroz is a 28 year old who spent most of last season in AA. Feierabend is unbelievably still only 25, but that's three years older than when he was unbelievably still only 22, and he's got nothing. And Seddon was probably better than White but worse than Jesus Colome, and this team saw fit to get rid of Colome in June. With Don Wakamatsu long gone and a new guy with zero ties to the organization in charge, the front office can finally stop pretending like Sean White has much of anything to offer to a Major League baseball team.
The Mariners may not go on to fill these 40-man roster spots with exciting and capable stars, but new blood is all I ask. Of the lesser players, Langerhans is the only one of these guys I'd maybe want to see in Seattle ever again.
Update: turns out the Diamondbacks grabbed Brian Sweeney off waivers as well. Brian Sweeney struck out four guys in his first four innings. He struck out ten in his last 33. Sweeney's the kind of heartwarming story that bad teams like to publicize, and for which good teams have little place. Surely Sweeney's all contact/flyball strategy will allow him great success in Arizona.
2nd Update: Casey Kotchman refused assignment and has become a free agent.