I have recently been looking at using Oracle subscribers in a SQL Server 2005 transactional replication topology. The main gotcha's I have identified are that the distributor can no longer co-exist on the subscriber (as a remote distributor to offload the log reader agent processing) and propagated schema changes will cause the subscription to be reinitialised. These are fairly important factors, particularly when we are talking about OLTP and terabytes of data. There are a bunch of other details listed in BOL under non-SQL Server subscribers http://technet.microsoft.com/en-us/library/ms151864.aspx which you should be aware of.
The good news? Not much I'm afraid, apart from the fact that the Oracle 10g R2 provider supports x64 and IA64.