Plaxo taking on Linkedin

Stealthily contact management site Plaxo has been adding functionalities to take on business networking site Linkedin as well as trying to become a platform for people to integrate their disparate online personas (like Friendfeed for example)

So when I logged in today to Plaxo (I am still a Linkedin regular :-) I noticed that Plaxo has added people search abilities.
Then there's the option to add your professional profile, which you might agree does not link very clearly to its stated position of being a "address book for the web"
But Plaxo's most interesting feature is Plaxo Pulse which tells you what your connections have been twittering, blogging or connecting with others.

In fact, one can now setup a public profile that can been seen by others with a easy to remember URL like mine is http://gautam.myplaxo.com/

Should Linkedin be worried? Maybe not in the short term, since Plaxo is still limited to the early adopters and its earlier privacy concerns haven't really gone way. However, if Linkedin does not iron out its performance issues, people might start using Plaxo increasingly more.