Paul Thurrott wrote in his article on windowsitpro.com that “Office 2010 for Windows, meanwhile, will become generally available June 15, 2010″.The Office 2010 will be available in the following editions.
Starter Edition
Home and Student Edition
Home and Business Edition
Professional Edition
Professional Academic Edition

There will be a free of  version Office 2010 that includes Microsoft Word and Excel, but comes with limited functionality and includes advertisements.

The prices of different version of Office 2010 are given below.
Office Home and Student:          Boxed Product $149      Product Key Card $119
Office Home and Business:        Boxed Product $279      Product Key Card $199
Office Professional:                       Boxed Product $499     Product Key Card $349
Office Professional Academic: Boxed Product $99        Product Key Card N/A

Via neowin.net