According to Wikipedia, Wallace's 40-time was 4.33s. For comparison's sake, The Ginn Family purportedly ran a 4.28 (but he didn't participate in combine workouts, so...).
I was able to dig up this nugget from 2008:
Following are the best 40 times and results in other events recorded by NFLDraftScout.com since 1999.
40-Yard Dash Times
4.24 - Rondel Melendez, (WR), Eastern Kentucky - 1999
4.28 - Jerome Mathis, (WR), Hampton - 2005
4.28 - *Champ Bailey, (CB), Georgia - 1999
4.29 - Stanford Routt, (CB), Houston - 2005
4.29 - Jay Hinton, (RB), Morgan State - 1999
4.29 - *Fabian Washington, (CB), Nebraska - 2005
4.30 - Yamon Figurs (WR), Kansas State - 2007
4.30 - Darrent Williams, (CB), Oklahoma State - 2005
4.31 - *Johnathan Joseph, (CB), South Carolina - 2006
4.31 - Aaron Lockett, (WR), Kansas State - 2002
4.31 - Santana Moss, (WR), Miami - 2001
4.32 - *Troy Williamson, (WR), South Carolina - 2005
4.32 - *Chad Jackson, (WR), Florida - 2006
4.32 - Jason Hill (WR), Washington State - 2007
4.32 - Tim Jennings, (CB), Georgia - 2006
4.32 - Chris McKenzie, (CB), Arizona State - 2005
4.32 - Tim Carter, (WR), Auburn - 2002
4.32 - Kevin Garrett, (CB), Southern Methodist - 2003
4.32 - Antwan Harris, (CB), Virginia - 2000
4.33 - Carlos Francis, (WR), Texas Tech - 2004
4.33 - Karsten Bailey, (WR), Auburn - 1999
4.33 - Chris Chambers, (WR), Wisconsin - 2001
4.34 - *Ahmad Carroll, (CB), Arkansas - 2004
4.34 - Domonique Foxworth, (CB), Maryland - 2005
4.34 - Tyrone Calico, (WR), Middle Tennessee State - 2003
So yeah, 4.33s is still damn fast.
I played against Fabian Washington my sophomore year in highschool...he went to Bayshore High. Their whole team was horrible and the OLmen were way undersized, but they ran sweep plays the whole time (he was a RB at the time) and killed us like 31-7. We knew what play was coming, but he was so fast we couldn't do anything to stop him. It was unbelievable how fast he was.