Thanks for the comments. We are actively working on this feature and will provide an update in the next few weeks.

The email alias functionality is now available allowing you to send emails from alternative addresses e.g. support@domain.com, bookings@domain.com

Documentation is located here:

http://www.workbooks.com/help/email_accounts

http://www.workbooks.com/help/email_settings

When importing leads the match option can be selected. Matching on email address will prevent duplicates. Additionally, when you convert a lead you are presented with a screen asking which objects (Person, Organisation, Opportunity) you wish to create. If a similar Person or Organisation already exists they will be displayed in the “duplicate” list.
Having said that, we are aware of the requirement to merge records. Typos, and the human factor will always have potential to allow duplicates to be created. When this happens a merge would be very handy to merge notes, emails etc onto one record.

We are implementing a Process Engine solution to deliver similar functionality in a flexible solution. It will be targeted at Sales Lead and People de-duplication.
(#2537)

This is currently underway and expected in the next release (Q2 2012). You will be able to use filters within landing pages to select large numbers of records and carry out operations including reassignment, deletion and setting values.