2003 1.8 turbo start up noise

I have a 2003 VW Jetta with the 1.8 turbo. It has about 150 K miles on it now. The car runs great but lately when I start it up the engine is making a loud humming noise, almost like a turbine spinning (almost sounds like a high pitch whistle). It only lasts about 1 minute but does kick back on sometimes while driving. It doesn't seem to matter if I increase the RPM's or not, the noise stays the same. Has anyone ever heard of this or know what it is?

Turbo whine is what it is called. With your mileage, it's most likely your turbo bearing wearing out and or the gasket has a leak. Drive it until the whine is constant and unbearable. Then have the turbo rebuilt or replaced with a new one. Either way you're getting more out of your turbo than most. 150k nice!
Franco