What Is This?

I got this in webmastertools what is its meaning

User-agent: Mediapartners-Google
Disallow:

User-agent: *
Disallow: /search

Sitemap: http://mobileplanet-waryam.blogspot.com ... by=updated

That is the content of a robots.txt file

On:
User-agent: Mediapartners-Google
Disallow:

User-agent: Mediapartners-Google = This indicate the Robot tipe ( from where and who is the robot ) in this case Mediapartners-Google (used for Adsense)

Disallow: = This indicate what sections of your blog the robots can visit

On:
User-agent: *
Disallow: /search

User-agent: * = The "*" indicate all robots, so this is for all robots that visit your site (ie, Yahoo, Bing, Google )

Disallow: /search = Indicate that pages on the folder "search" can't be indexed by the robots

So in this case you see that all robots can visit your site but can't index pages like http://mobileplanet-waryam.blogspot.com/search/

Finally where says:

Sitemap: Sitemap: http://mobileplanet-waryam.blogspot.com ... by=updated

Indicate to all robots where is located the sitemap of your blog

More on Robots.txt can be found here:
http://en.wikipedia.org/wiki/Robots_exclusion_standard