The NFL distributes these extra choices during its spring meetings (scheduled for March 22-25 this year). The leauge uses a complicated formula to award picks to teams as compensation for the free agents they lost in the previous year. Note: Teams cannot trade compensatory picks.
AdamJT13 has figured out the formula well enough to provide largely accurate projections. I have used his projections to show how many total picks each NFC West team might have in the 2009 draft.
The asterisks reflect totals affected by AdamJT13's projections. He expects the 49ers to gain one choice in each of the fifth and sixth rounds. He expects the Seahawks to gain four seventh-round choices. He expects the Cardinals to gain on seventh-round choice.
I know NFL executives who say they can accurately forecast the rounds for all compensatory picks. AdamJT13 comes closer than anyone I've seen outside an NFL organization -- assuming he does not work for an NFL team. His identity remains unknown to me and others. If you know him or if you are him, we'd love to learn more. His blog is here.
Note: Kingz49ers asks if the 49ers lost Justin Smiley as an unrestricted free agent. They did. Smiley signed with the Dolphins for $5 million per season. He started 12 games, which probably works out to about 70 or 75 percent of the offensive snaps.
AdamJT13 follows up: To answer Kingz49ers's question, the 49ers lost Justin Smiley, Kwame Harris, Marques Douglas and Maurice Hicks, and they signed Justin Smith and Bryant Johnson. Smith had by far the highest value, and he cancels out the loss of Smiley. Johnson has the same value as a seventh-rounder. If Douglas' value is in the seventh round, Johnson cancels out him, and the 49ers get a seventh-round comp pick for Hicks. If Douglas' value is in the sixth round, Johnson cancels out Hicks, and the 49ers get a sixth-round comp pick for Douglas.