Per MLB.com's T.R. Sullivan, on Twitter.
These two signings are kind of interesting in the sense that they, like Brad Hawpe, could both end up seeing some time at the major league level this year. That may prove especially true in Beimel's case, as the Rangers lack a guaranteed southpaw out of the bullpen since Darren Oliver jumped to the Blue Jays, and Beimel has proven himself effective in that role at various times in the past:
Beimel, who turns 35 in May, turned down the Rangers' offer of a minor league contract back in January 2009, and proceeded to have a decent year between Washington/Colorado -- which, of course, doesn't say much about his expected utility now, and doesn't mean he has much left in the tank after a homer-tarnished 2011 season, but one can see how the dugout's longing for a veteran lefty could end up vaulting Beimel right into the mix for an Opening Day bullpen spot.
Jackson *, 29, has been a terrible hitter over the last three years (.232/.312/.323, 73 OPS+), and while I suppose there's an outside chance the Rangers can recapture the .300/.370/.450-hitting form that he displayed on an annual basis from 2006-08 (and which was seemingly derailed by a long-duration infection called "valley fever"), I imagine signing Jackson is more about adding a little extra insurance behind first base and the corner outfield spots, where the Rangers have an injury-prone Josh Hamilton and Nelson Cruz and a still recuperating Mitch Moreland.
The Rangers now have 58 players on their spring training roster.
[* Today's fun fact: Four and a half years ago, the Rangers reportedly demanded a package comprising Jackson, Carlos Gonzalez, and a pitching prospect from the Diamondbacks in exchange for Mark Teixeira.]