Microsoft Exchange 2010 includes a new (and great) feature, called online archive, which enables you as an IT administrator to provision your mailbox-enabled users with a familiar personal archive, available online, providing you with a lot of features to preserve and discover e-mail data.
And there is Microsoft Exchange Hosted Archive, which is available now, and can be summarized as "a centralized, easily accessible, and multi-functioning e-mail and IM repository to assist organizations manage increasingly complex retention, compliance, e-discovery, and regulatory requirements" (as taken from the MsOnline site).
If you want to know more about the archiving features included with Exchange 2010, head over to the following site:
And if you want to know more about Exchange Hosted Archive, head over to this site:
To answer a very recurring question: can we upload historical data to Exhange Hosted Archive?
The answer can be found in this document:
Upload Historical Data to Exchange Hosted Archive 9.2
This page needs to be updated since EHA has been end of lifed and EOA is out. Where can we find documentation on EOA configuration in a Rich Coexistence environment?