timestamp of the last replayed transaction

Hi,

After 9.0 release, I've often heard that some people want to know
how far transactions have been replayed in the standby in timestamp
rather than LSN. So I'm thinking to include the function which returns
the timestamp of the last applied transaction (i.e., commit/abort WAL
record) in the core.

Name: pg_last_replay_xact_timestamp (better name?)
Return Type: timestamp with time zone

Thought?

Regards,

-- 
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center