After Google twitter accounts, here are the Microsoft twitter accounts
Products & Services
MSWindows - For Microsoft Windows
ie - Internet Explorer
Bing - Bing search engine
bingcashback - Bing Cashback
WindowsLive - Microsoft Windows Live
liveframework - Windows Live Framework
livemesh - Windows Live Mesh
wlmessenger - Windows Live Messenger
SharePoint - SharePoint
bizspark - Microsoft BizSpark
zunemarketplace - Zune Marketplace
wmdev - Windows Mobile Development Team
microsofttag - Microsoft Tag
Office_Live - tweets from the Office Live Team
officelabs - Microsoft Office Labs
MSOfficeResKit - Microsoft Office Resource Kit Team
Microsoft_Xbox - Xbox
MSMyPhone - Microsoft My Phone Team
msaccess - Microsoft Access
SilverlightNews - Silverlight News (by Dave Campbell)
fixit4me - Microsoft Fix It
Live_at_edu - Microsoft Live
MSSurface - Microsoft Surface
Blogs, Communities, and Websites ZuneInsider - ZuneInsider blog
ch9 - Channel 9
ch10 - Channel 10
ch8 - Channel 8
mixonline - Mix Online
MIX09 - The MIX09 Conference
AskTechNetUK - TechNet UK
SiteNamedDesire - A Website Named Desire
MSDN - Microsoft Developer Network
codeplex - Microsoft's open source project hosting site
MSExpression - Microsoft Expression Community Site
XNACommunity - XNA Creators Club
Corporate
adCenterBlog - Microsoft adCenter
MicrsftTech4All - News from Microsoft Accessibility team
MicrosoftStore - The Microsoft Store
MicrosoftPress - Microsoft Press
Microsoft_Green - Environmental Sustainability at Microsoft
MSAdvertising - Microsoft Advertising
msPartner - Microsoft Partner Program
MVPAwardProgram - MVP Award Program
MSLearning - Microsoft Learning
MicrosoftUP - Microsoft Unlimited Potential
MSFTResearch - Microsoft Research
MSRobotics - Microsoft Robotics
bizspark - Microsoft BizSpark
Other
XAMLEvents - Silverlight and WPF events
projectrosetta - Chronicling the trail from Flash to Silverlight
ContinuumShow - Exploring the world of the Microsoft Client Continuum