Viable strategies for rebuilding indexes online in SQL Server 2008 R2 Standard edition?
Assuming these are non clustered indexes then the CREATE INDEX topic on BOL discussing offline operations indicates this approach should only partially work in that it will allow read only access to the table but will still block updates. The relevant section is below (emphasis mine)


  Table locks are applied for the duration of the index operation. An
  offline index operation that creates, rebuilds, or drops a clustered
  index, or rebuilds or drops a nonclustered index, acquires a Schema
  modification (Sch-M) lock on the table. This prevents all user access
  to the underlying table for the duration of the operation. An offline
  index operation that creates a nonclustered index acquires a Shared
  (S) lock on the table. This prevents updates to the underlying table
  but allows read operations, such as SELECT statements.