The folks at Slacker are anything but slackers, but last month’s announcement that Slacker would phase out its G2 player leaves a hole in its portable player portfolio.

One of the main differentiators of the Slacker service is its ability for it to cache radio stations using Wi-Fi. Slacker’s first player was a rather unsatisfying effort that, for example, had a hard time remembering WPA passwords. The G2 was much improved, although hardly competitive with the best experiences from Apple and Microsoft in terms of portable music players.

Dropping its own branded player makes a lot of sense for Slacker. Helped by Verizon Wireless’s distribution, the company has had great success with its BlackBerry client, but which only now can cache over Wi-Fi with the BlackBerry Storm 2. Slacker is also able to cache stations on Sony’s X-series Walkman, but hat’s a $300 device. So for the short-term, anyway, the end of the Slacker G2 will leave a price-functionality hole for those wanting to listen to the Slacker service offline and on the go. Perhaps dropping support for the G2 will free up some engineering resources to finally implement caching on the iPhone and iPod touch as the Rhapsody team intends to do.

Regardless, Slacker is clearing out the G2 for $129 and throwing in a free dock.