in SQL200x products replication is FREE (unlike competing vendors)

exceptions

1. if doing Oracle-SQL replication you would need SQL2005 Enterprise Edition

2. SQL/Express and SQLCE can be subscribers (not publisher or distribution engines)

BTW, you can

A. have immediate/queued updating for transactional

B. have merge repl and peer-peer if such topologies are required

C. replicate from SQL to non-SQL via OLEDB/other data providers

if you have a mobile scenario you should also look at ADO Sync (new functionality in Beta)

HTH

Dick