The Seahawks have been making moves picking up guys from other teams' cuts, as they are wont to. As many predicted, the first point to address was the defensive line.
The team signed DE/DT Landon Cohen, waived by the Patriots. Cohen was a 7th-round pick of the Lions back in 2008. He signed with the Jaguars in 2010, and with the Patriots later that year. In 2009, he played 14 games as a DT for the Lions, starting 4. He's listed as 3-4 DE with the Patriots. At 6'3, 300 lbs, he's swing depth, probably at the 5-tech or 3-tech. Reading Cohen's scouting reports reminds me of DT Clinton McDonald, an undersized pass rushers with good first burst, though he's gained a lot of bulk since his college days, which probably impacts his abilities as a run defender.
The Seahawks also claimed DT Al Woods, who was waived by the Buccaneers. Woods was a 4th-round pick by the Saints in 2010. He didn't last with them, being waived before the start of the season. The Steelers added him to their practice squad, and then the Bucs signed him off the Steelers practice squad in November. He was active for 9 games with the Bucs, so has no practice squad eligibility anymore. With the Bucs, he primarily played 4-3 nose tech, but according to Bucs Nation's Sander he can play both. He was cut by the Bucs primarily because their defensive line is very deep, with a lot of their own high draft picks, rather than because he lacks skills.
Both these additions are to the 53-man squad so we should be hearing about cuts soon.
Addendum: Looks like Pep Levingston will be waived.