I found a solution for the search problem but I am not able to post it since MSN sucks today!
It seems that Gallery was changed but some M$ stuff did some brainless work and so it does not work as expected …
e.g. If you like to install the Twitter Notify plugin and searching for that plug-in at the Gallery you will not find it!
List of all plug-ins: http://plugins.live.com/writer/browse?orderby=featured
Greetings to Redmond!