There's nothing new with the Mariners. At all.
One situation worth keeping an eye on is taking place in Denver, where the Rockies are trying to sign Jason Jennings to an extension. Attempts thus far have been unsuccessful, and if they can't agree on anything then Jennings'll become one of the more obvious and desirable pitchers on the market. Were that to come to pass, the Mariners would definitely be interested; we've been hearing his name for a while, now, and with a free agent pool bearing rotten fruit the front office will likely have to acquire at least one starter via trade.
The problem, aside from competition, is that the M's and Rockies aren't really a good fit - Colorado's looking for a starter and center fielder in return, and while Jeremy Reed's probably living out of an underachieving left-handed suitcase right now, he's not that much better than what the Rockies already have. And any request on O'Dowd's part for Adam Jones will promptly be turned down. Although things could change, this seems like a situation where it's the right player and the wrong match.
More fun inspired by reading The Book blog - tracking how often hitters reach base on errors. You always hear about how speedy guys like Ichiro or Jose Reyes can force defensive miscues by sprinting down the line, and sure enough, they're right there near the top of the list, Ichiro reaching 16 times and Reyes 15. Speed isn't the only weapon, though, as you also have guys like Joe Mauer and Albert Pujols hanging around in double-digits (I'm guesstimating that the league average is somewhere around 8 or 9). Strangely enough, the Mariners had three of the top beneficiaries in the league, with Ichiro, Lopez, and Beltre combining to reach base 46 times on errors this past season. Some of that probably has to do with hometown scoring, but even so, that's a swing of at least a win or two in Seattle's favor over the average.
So the question then becomes, is this a repeatable "skill"? I can't say off the top of the top of my head (I'm sure somebody out there knows, but I don't), but it's interesting to think about. Raw numbers don't mean much by themselves, since RBOE (Reaching Base On Error) is highly dependent on accumulating at bats and consistently making contact, so let's look at a handful of rates:
Ichiro: 1.97 RBOE per 100 balls in play
This is hardly an exhaustive study, but there's not that much spread in the data - the difference between the two extremes is roughly 5-6 times reaching base per season, or ~3 runs. And that doesn't even begin to take into account ball in play type, since grounders are booted way more often than fly balls.
I think speed contributes to errors, but that the actual effect is overstated. Someone like Ichiro might force an extra error or three over the course of a season than an average runner, but even that's questionable, since Adrian Beltre - who's hardly considered fleet of foot - has a higher rate. (Which leads me to wonder if errors are caused by the perception of speed, rather than by speed itself, since Beltre always looks like he's busting his ass down the line.)
Fun idea, but on the surface I'm not seeing much there. That said, I probably need a copy of The Book to know for sure.