It's important to take every milestone in perspective.

"On Christmas Day, for the first time ever, customers purchased more Kindle books than physical books," reads an Amazon.com (NASDAQ:AMZN) press release over the weekend.

It's an impressive visual. Picturing digitally-delivered books outselling old-school bound reads is a head-turning moment.

However, that's when logic kicks in:

  • It's Christmas, so all of the Kindles that have been delivered over the past few weeks as gifts are finally meeting their owners. They're empty. They're hungry.
  • There aren't any shipments going out on Christmas, so it doesn't make sense to place an order for a physical item.
  • Amazon has been promoting the Kindle on its landing page for more than two years. This day was going to come eventually.

Don't get me wrong. It's certainly cool that this happened, but wake me up when it happens on a typical operating day.

In the meantime, Amazon also announced some of its category bestsellers in terms of units shipped. There are some meaty implications for investors.

In the electronics category, the Kindle was the big winner. Apple's (NASDAQ:AAPL) entry-level iPod touch followed. Those two items are no-brainers. The bronze medal goes to Garmin's (NASDAQ:GRMN) nuvi 260W 4.3-inch GPS. Amazon may have been practically giving them away -- they were at $129.99 last night -- but it's still impressive to see Garmin muscle its way onto the list. The widening proliferation of smartphones and other mobile devices with navigational functions appeared ready to dig a grave for Garmin. Not so fast, I guess.

Good news for Green Mountain Coffee Roasters (NASDAQ:GMCR)? The top two grocery items were K-Cup refills from Diedrich Coffee's (NASDAQ:DDRX) Coffee People brand. 

Bad news for Green Mountain? Reusable K-Cup filters -- which mean that java junkies don't need to buy actual Keurig K-Cup refills for their machines -- were the top draw in Amazon's Home & Garden category.

Another notable nugget is that Microsoft (NASDAQ:MSFT) scored two of the three software bestsellers, but none of them were Windows 7. It was the PC and Mac versions of Microsoft's Office suite that landed on the list.

Thanks for the morsels, Amazon, even though some are meatier than others.

Read Amazon's press release and share your insights in the comment box below.

Green Mountain Coffee Roasters is a Motley Fool Rule Breakers recommendation. Apple and Amazon.com are Motley Fool Stock Advisor selections. Microsoft is a Motley Fool Options pick. Microsoft is a Motley Fool Inside Value selection. Try any of our Foolish newsletter services, free for 30 days.

Longtime Fool contributor Rick Munarriz has been shopping online for about as long as Amazon.com has been in business. He owns a Kindle. He does not own shares in any of the companies in this story. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.