++++++++++  Xcode Property Creator ++++++++++
tested with Xcode 3.2.2

To use:
Xcode > Scripts Menu > Edit User Scripts...
Add new User Script > Add Script File...
Select the PropertyCreator.pl
Assign a shortcut (Optional)

Select some instance variable declarations and execute script. Example input:
@interface Temp : NSObject {
	NSString *temp;
	NSArray *array_;
@private
	NSMutableSet *privateSet_;
}

Script will generate both public and private property declarations as well as add synthesize and release statements.

Screencast showing it's usage can be downloaded here:
http://cl.ly/1nVI

Inspired by: 
http://cocoawithlove.com/2008/12/instance-variable-to-synthesized.html

Created by Matt Gallagher on 20/10/08.
Copyright 2008 Matt Gallagher. All rights reserved.

Enhancements by Yung-Luen Lan and Mike Schrag on 12/08/09.
(mainly: multiple lines)
Copyright 2009 Yung-Luen Lan and Mike Schrag. All rights reserved.

Enhancements by Pierre Bernard on 20/09/09.
(mainly: underbar storage name, behavior, dealloc,…)
Copyright 2009 Pierre Bernard. All rights reserved.

Enhancements by Chris Jensen on 27/05/10.
(mainly: underbar after storage name and moves declaration of private variables to implementation)
Copyright 2010 Chris Jensen. All rights reserved.

Permission is given to use this source code file without charge in any
project, commercial or otherwise, entirely at your risk, with the condition
that any redistribution (in part or whole) of source code must retain
this copyright and permission notice. Attribution in compiled projects is
appreciated but not required.