While on the topic of Slim there is now an ultra small or slim bluetooth GPS unit launched by Navicore. The device weighs just 30g and measures 6.4 x 2.2 x 1.5 and includes a built in rechargeable battery, SiRFS SiRFstar III GPS chip. The battery is claimed to have a life span of 8 hours which is pretty good.
Via: TechEBlog