Gilbert Gardner - Signed a one-year contract with the Lions on 03/24/08 and is due a base salary of $605,000. No other financial details were disclosed. Gardner signed for the league minimum for players with four credited seasons and his contract likely qualifies for veteran minimum treatment with the NFLPA subsidizing $160,000 of Gardner's contract. He may have received a $40,000 signing bonus, but my guess is that he didn't receive a signing bonus. If he received a $40K signing bonus, his current year cap cost would be $485,000, if he didn't receive a signing bonus, his current year cap cost would be $445,000.
Alfred Fincher - Signed a one-year contract with the Lions on 03/26/08 and is due a base salary of $520,000. No other financial details were disclosed. Fincher has three credited seasons and therefore his contract would not qualify for veteran minimum treatment. He likely did not receive a signing bonus and his current year cap cost would be $520,000.
Top 51 Rule - During the off-season (March 1st until final cuts), only the top 51 player contracts count for salary cap purposes. The Lions currently have 71 players signed for the 2008 season and 20 of those contracts count $445,000 or less. Any contract that the Lions sign for less than $445,000 would not effect the cap. Any contract that is for more than $445,000 would only effect the cap by the amount in excess of $445,000.
Gilbert Gardner's contract did not effect the Lions current cap status as his cost was $445,000. Albert Fincher's contract would cost the Lions $75,000 against the cap. ($520,000-$445,000).
Based on the above transactions, I'd estimate the Lions current cap status at $1M under the cap.