October 27th, 2009:

BitWise IM 1.7.3 has been updated for Windows 7. This release fixes a bug on Windows 7 that causes the corner status popup windows not to close properly. After updating, BitWise IM will identify itself as version 1.7.3a.

Free, ad-free IM for home/personal use(previously called BitWise Chat)
Encrypted, Cross-Platform, Instant Messaging for Windows, Mac OS X, and Linux

http://www.bitwiseim.com/