Can’t get a white MacBook? An update might be coming.

When supplies of certain Apple products suddenly become scarce, Mac fans take notice. It often means that the product or model in short supply is being phased out to make way for an updated version.

Wednesday, AppleInsider reports the availability of Apple’s current $999 white MacBook “has become constrained.” Eeee! Shiny, new, entry-level white computers could be on the way! Will they still have a polycarbonate shell?!

No one, including AppleInsider, has received any word from Apple on a refresh, but it’s been a year since the MacBook was last updated. AppleInsider noted that the authorized resellers in the Mac Pricing Guide are completely sold out of white MacBooks. Those resellers include AmazonMacConnectionOn Sale and J&R.

The drop in supplies could also be due to a the white Macbook’s reduced price to $899 from $949. Consumers can purchase an 11-inch MacBook Air at a similar price ($999). MackBook Air has an 1.4GHz Intel Core 2 Duo processor with GeForce 320M graphics. Current MacBooks have GeForce 320M graphics and an Intel 2.4GHz Core 2 Duo processor.

We assume no new computers will be released until Mac OS X 10.7 Lion drops this fall. This week we also reported on the mysterious Macbook Air shortages that could presage another refresh. Eeee!