Version:           4.4.2 (using KDE 4.4.2)
Compiler:          gcc-4.5.0 gcc version 4.5.0 20100416 (release) (PLD-Linux) 
OS:                Linux
Installed from:    Unlisted Binary Package

After upgrade to 4.4.2 my sftp://user@host/dir connections using public key authentication stopped to work. It used to work for sure in 4.3.x and probably even in 4.4.0. Using fish:// work with same connection parameters though.
Not sure how I can provide more debug info.
In konqueror I can see:

The requested operation could not be completed
Out of Memory
Details of the Request:
URL: sftp://some.host.on.my.vpn
Protocol: sftp
Date and Time: Saturday 08 of May 2010 11:58
Additional Information: 
Description:
The program on your computer which provides access to the sftp protocol could not obtain the memory required to continue.