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It's a product of Disk Utility's strangeness. Be thankful the deleted partition wasn't at the beginning of the drive or you'd have a massive headache to deal with. If the lost space really bothers you, back up your stuff and reformat the entire drive to return it to the original size.
 
How would I back up my stuff? I have an external hard drive that's big enough, just don't know what to do. I also have iWork '08, and if I reinstall, I wouldn't have to repurchase it or anything right?

If you can completely erase your external drive, download Carbon Copy Cloner. Use Disk Utility to format the external drive to Mac OS Extended (Journaled). With Carbon Copy Cloner, clone your MacBook's hard drive onto the external drive.

Now restart your MacBook while holding down the option key. After a few seconds, a menu will appear allowing you to select a partition to boot from. Choose to boot from the external hard drive. Your system should run exactly as before. Repeat the process, formatting the MacBook's hard drive (to one partition!) and cloning the external drive back onto the MacBook. Don't worry, if you have accidentally booted from the MacBook's internal drive, Disk Utility will simply refuse to format it.

I think the manual method described in http://support.apple.com/kb/HT1553 is good enough for me.
First time I installed Linux, no problems, but then I accidently erased the partition, and then the missing free space 268 MB would never add to my HFS+ Mac partition. Now when I shut down, it takes like 90 seconds, way slower than before. Would this be related to my partitioning troubles?

I can't see how it would be, no. :confused: The format may fix this problem as well, though.

I wouldn't suggest using Apple's method. It leads to a lot more work since you would then have to reinstall your operating system.
 
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