No word yet on the compensation, but it looks like the Lions have now found their starting left guard. With Dominic Raiola penciled in at center, Stephen Peterman set to return from injury to start at right guard, and no indication that Jeff Backus or Gosder Cherilus are going anywhere, it looks like the Lions' starting offensive line may now be set. There's always the chance that the Lions could draft an offensive lineman to improve depth or build toward the future, but for now I'd say there's a pretty good chance that the day one starting lineup for the O-line is now in place.
I will have more on this deal as it becomes available.
UPDATE: Schefter is now reporting that the Lions will send a fifth-round pick to the Seahawks in exchange for Sims. Had the Lions signed Sims to an offer sheet, the Seahawks would have received a fourth-rounder as compensation assuming the offer went unmatched. Because Sims signed his tender last week, however, the Lions had the ability to negotiate whatever terms they wanted to acquire him, and that turned out to only be a fifth-round selection. Considering Detroit acquired a player who will likely start at left guard for only a fifth-rounder, this is another job well done by Martin Mayhew.
UPDATE II: Check out what draft picks the Lions now have after the jump.
Round 1 - #2 (2)
Round 2 - #2 (34)
Round 3 - #2 (66)
Round 4 - #2 (100)
Round 7 - #7 from Cleveland (214)
Round 7 - #48 (255)