d20 Modern/Urban Arcana are a step towards Shadowrun, but there's still a few things missing. Chief among them are cybernetics and the matrix (or whatever Shadowrun called it). You may have to tweak the races some, account for allergies, deal with totems, etc. Plus consider that d20 Modern is, well, modern and Shadowrun is approximately 50-60 years in the future.
If a person were to take d20 Modern, Urban Arcana, and OGL Cybernet, they could come out of it with a fairly good d20 version of Shadowrun, rules-wise. You would have to make some tweaks, of course.