The Hawaii Winter Baseball league started near the end of September, so the teams have played 10-11 games to this point. The Arizona Fall League started on the 7th of October.
The Caribbean leagues start next week in most cases - most high-level M's prospects/players end up with the Lara Cardenales in the VWL, but Wlad and a few prospects will be playing in the Dominican instead. J at Mariner Minors will probably cover these leagues, and has the wrap-up on M's representatives in the Baseball America top 20 prospects in each minor league.
The M's have several prospects in the prestigious Arizona Fall League this year, headlined by Carlos Triunfel and Greg Halman. Triunfel is the youngest player in the league by a wide margin, and Halman would vie for that spot if Triunfel wasn't around. Despite this, they're both off to hot starts. Halman has played every OF spot and is off to a 6-13 start with a 2B and only 2 Ks. Triunfel has played 2b and SS and is 5-13 with 3 2Bs, 1K and 1BB.
Rob Johnson is the injury replacement for Adam Moore, but has played only one game behind the plate, with one appearance as a DH.
The pitching 'spects in Peoria include Joe Woerman, Doug Fister, Stephen Kahn and Gaby Hernandez. Fister, Woermanand Kahn have each thrown 1 scoreless inning so far.
The HWL restarted a few years back as a league for low-minors prospects *and* advanced prospects from Japan (the NPB players seem older; I'd guess quite a few are corporate league vets). Given that the players weren't as advanced as AFL guys, expectations weren't terribly high. However, with draft hold-outs, injuries, etc., the league has managed to nab some of the better prospects in the game, often before they become household names. Ian Kennedy, Joba Chamberlain, Jeff Clement and Rick Vanden Hurk were all members of the original class in 2006, and Matt Wieters made his pro debut there last year. This year, the league's headlined by 1st round picks Buster Posey, Yonder Alonso and 2007 1st rounder (and TJ surgery veteran) Andrew Brackman.
The only M's name of any note is Cuban 1B prospect Johan Limonta. He's been old for his league in 2007 and 2008, but he's a 1B prospect who could take a walk, so he was at least moderately interesting. So far, he's uh... he's struggling. In 29 at bats, he's got 3 hits and has struck out a remarkable 14 times with 0 walks. SSS, sure, but... oww. He's also had some time in LF, so we'll see if he plays more OF in West Tennessee next year.
The other M's farmhands on the Waikiki Beachboys include Jamie McOwen, who's been batting leadoff and playing CF, and pitchers Rob Harmon and Steven Richard.