Since it's not usually a major issue, and can't be fixed while SQL's running, and it pretty immaterial on a SAN, not really.
But it you want. Google: file system fragmentation
It's not a SQL thing, it's an OS thing.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability