Seems like more and more producers are using laptops as main DAW these days. I'd like to go the same route myself, and have my eyes on the new Macbook Pro Retina.

Having used desktops for years and being used to 3 hard drives; OS/daw drive, sample library drive and record drive, how are you laptop guys solving this? Two external hard drives? One external hard drive for sample libraries? Or are the new MBP simply fast enough to handle everything?

The new MBP is fast enough to handle everything, but it comes with 256 GB stock.

I'd recommend to consider one external Thunderbold RAID drive at least. They can be daisy chained so upgrading to more drives is not a issue.

Integrated HDD, so no swapping. External or die.
Integrated RAM, so no swapping. Comply or die.
Integrated battery, so no swapping. Dead is dead.

I always wanted a MacBook Pro.
Not anymore.

@chokehold HDD seems to be swappable but not right now due some proprietary connector. It's a matter of time until we see 3rd party selling them.

From my experience I only needed to upgrade the stock RAM a couple years after the purchase, so getting the 16 GB OTB seems the best choice.

Regarding battery, I'm with you. Getting it glued was a very bad decision just for the extra thinness. Apple just want your 200 EUR to replace it on their tech service.

If going for one external TB HD, should it be used for sample libs, audio drive or both?

For both should be enough. Also, check:

http://store.apple.com/us/product/H7150ZM/A/lacie-little-big -disk-thunderbolt-series-hard-drive

@ George, thanks for chiming in. The TB HD you linked seems perfect, it appears to have two internal SATA drives which would definitely fit my needs, albeit it's a bit on the pricey side.
Does drive speeds in TB HD's matter? My local hardware dealer sells the "Little Big Disk" series in 5400 and 7200 rpm models.