The press release says it all:
Press conference and live webcast to take place at Mobile World Congress 2010.
REDMOND, Wash., Feb. 10
What: On Feb. 15, 2010, Steve Ballmer will host a press conference to discuss Windows® phones at Mobile World Congress 2010.
Who: Steve Ballmer, CEO, Microsoft Corp.
When: 3-4 p.m. CET
Where: The Garden Room
Catalonia Barcelona Plaza
Plaza Espana 6-8
08014 Barcelona, Spain
How to view: The live webcast will run at http://www.microsoft.com/news/windowsphone. An on-demand version will be posted after the event concludes.