$6M/1yr. Tejada was probably the best available free agent SS left on the market.
CHONE projects Tejada as a average hitter (-1 R150) and a below-average fielder (-12 runs per season). Houston fans had him dead-on average last season in the field. Jeff Zimmerman's UZR projections put him at -4 runs per season in the field. So overall, somewhere around a -5 run fielder at shortstop? CHONE projects him at 81% playing time.
Given this, and the fact that he plays a premium position, I think projecting him as a 2 WAR player next season seems reasonable. If the Orioles move him to 3B, he likely would be a roughly average fielder (good arm, less good range per fan scouting), though he'd lose some of his position adjustment. Call it an even swap.
If 1 WAR = $3.5M on this market (which seems about right), then he's worth about $7 M. We're well within the margin of error here, so this is a fair deal. Tejada would have been a nice upgrade to the Reds lineup this season, but I guess it speaks to how tight the purse is for the 2010 season (at least).