Lazarus is a multi-platform, feature-rich programming environment for the FreePascal Compiler that supports the creation of self-standing graphical and console applications. Also available for 64 Bit.
Free Pascal is a compiler capable of running on Linux, Win32, OS/2, 68K and more. It is designed to be able to understand and compile Delphi syntax, which is OOP (object-oriented programming).
Lazarus is the part of the missing puzzle that will allow you to develop Delphi like programs in multiple platforms. Unlike Java which strives to be a write once run anywhere, Lazarus and Free Pascal aim to write once compile anywhere. Since the same compiler is available on all of the above platforms, it means you don't need to do any recoding to produce identical products for different platforms.
Lazarus supports the user in creating graphical user interfaces (GUI) and command-line based applications on many platforms. It will meet the demands of most any programming task at hand.