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