Question: I am using Tridion 2009 SP1 for a client, we have jsp pages and vb script. Our client wants to switch to Tridion 2011 and have told to investigate Experience Manager. I tried searching on sdllivecontent but could find anything with this word. Can anyone direct me what actually is Experience Manager so that i can get back to client and estimate the efforts required when i migrate to Tridion 2011

Answer: 
Experience Manager is the product formerly known as the SDL Tridion User Interface (UI) update, formerly known as SiteEdit.

You can find information on Tridon World for UI Update 
(<https://www.sdltridionworld.com/downloads/documentation/UIU4SDLT2011SP1/index.aspx>) if you have access, as well on SDL Live Content
(<http://sdllivecontent.sdl.com/LiveContent/content/en-US/UIU4SDLT2011SP1/concept_EDC411EF58BD4700A8B6BD996AB102F3>).

I suppose the reasoning behind the re-renaming of the product is due to its becoming more integrated into the main Content Manager Explorer interface.
Though a lot of references are already mentioned in above answers. 
Here I would like to suggest you one point regarding the estimate. 

There are two possibilities in your case first is upgrade and other is migrate. Effort will vary in both the cases. 

Though you have already mentioned migrate in your question but I am not sure that you are differentiating it with upgrade.
If you go with the upgrade, your existing SiteEdit-enabled VBScript/JScript templating code only requires you to add a Javascript command and republish. Do bear in mind, however, that your templating code is deprecated.

Otherwise, if you will go with second option, migration would be part of a larger effort to migrate your VBScript templates to modular templating.