I suppose I use twitter the most and google reader occassionally, pushnote is new to me. Maybe by the time this is over I'll have been converted.
I find twitter very eay to use, but tend to use my facebook account more as it allows for more content. I have to say that I find rss more useful for current awareness than blogs or twitter feeds. twitter is great for seeing what is going on at other libraries and to keep an eye on techsource (ala), but I find I use a browser to search for content when I am researching a project, and if the results include a blog then fair enough, but otherwise I am not a frequenter of the blogosphere.
I must see if I can get a widget for twitter to post the content for our library account as news on the web site!!!