Why something like this isn't done by NSObject#dealloc is beyond me...

NSObject+AutoreleaseProperties.m

#import <objc/runtime.h>

@implementation NSObject (AutoreleaseProperties)

- (void)releaseAllProperties {
	NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
	unsigned int outCount, i;
	objc_property_t *properties = class_copyPropertyList([self class], &outCount);
	for (i = 0; i < outCount; i++) {
		objc_property_t property = properties[i];
		NSArray *propertyAttributes = [[NSString stringWithCString: property_getAttributes(property)
														  encoding: NSASCIIStringEncoding] componentsSeparatedByString: @","];
		// If this property needs to be released
		if ([propertyAttributes containsObject: @"R"] || [propertyAttributes containsObject: @"C"]) {
			// Find default setter name
			NSString *name = [NSString stringWithCString: property_getName(property)
												encoding: NSASCIIStringEncoding];
			NSString *setter = [NSString stringWithFormat: @"set%@%@:", 
								[[name substringToIndex: 1] uppercaseString],
								[name substringFromIndex: 1]];
			// Find custom setter name
			for (NSString *attribute in propertyAttributes) {
				if ([attribute hasPrefix: @"S"]) setter = [attribute substringFromIndex: 1];
			}
			// Set the property to nil
			[self performSelector: NSSelectorFromString(setter)
					   withObject: nil];
		}
	}
	free(properties);
	[pool release];
}

@end