I can confirm that this is an issue still in 1.6.2.
By MCP I am referring to Minecraft Coders' Pack, not MCPatcher. Also, Modloader is an API created by Risugami for Minecraft mods, it is required for mods created with this tool, it is not a third party installer as I assumed you thought.
Yes you will have to get a new copy. OptiFine and Modloader will not update until MCP is released for 1.4.5 but you can expect TMI to update in the next few days.
I tried the pre-release and it is not fixed for me, although I can direct connect with the IP + the port it displays.
Just to clarify Stefy, the 1.4.4 recommended build is exactly the same as the pre-release, so it could not have been fixed anyway.
I can confirm this also happens on Windows 7 x64 with Java 1.7.0_09 (Java 7 Update 9) which is the recommended build. On my iMac running OSX Lion, I can find the world with the auto search but cannot join as it is bound to the wrong port.
Me after I opened the world to LAN:
http://i.imgur.com/oBqrQ.png
ME finding it on the other computer but unable to join:
http://i.imgur.com/gVnoA.png
I think this is a major bug as it renders LAN unplayable, a huge aspect of post-1.3
You would also need a 3D capable monitor, they are very expensive.