The actual 10.6 EULA:
C. Leopard Upgrade Licenses. If you have purchased an Upgrade for Mac OS X Leopard license, then subject to the terms and conditions of this License, you are granted a limited non-exclusive license to install, use and run one (1) copy of the Apple Software on a single Apple-branded computer as long as that computer has a properly licensed copy of Mac OS X Leopard already installed on it. If you have purchased a Family Pack Upgrade for Mac OS X Leopard license, then subject to the terms and conditions of this License, you are granted a limited non-exclusive license to install, use and run one (1) copy of the Apple Software on up to a maximum of five (5) Apple-branded computers at a time as long as those computers are located in the same household (as defined above), are used by persons who occupy that same household, and each such computer has a properly licensed copy of Mac OS X Leopard already installed on it. The Family Pack Upgrade for Mac OS X Leopard License does not extend to business or commercial users.to the terms and conditions of this License, you are granted a limited non-exclusive license to install, use and run one (1) copy of the Apple Software on up to a maximum of five (5) Apple-branded computers at a time as long as those computers are located in the same household (as defined above), are used by persons who occupy that same household, and each such computer has a properly licensed copy of Mac OS X Leopard already installed on it. The Family Pack Upgrade for Mac OS X Leopard License does not extend to business or commercial users.
http://images.apple.com/legal/sla/docs/macosx106.pdf
I don't know how much clearer Apple can make it. If your a 10.4 Tiger user and you purchased the 10.6 Snow Leopard upgrade for $29, you're in violation of Apple's EULA.
Just because Apple didn't force an upgrade check or some other preventable measure, doesn't excuse the EULA violation.
Whether you care or not, is up to you.
End of story.
C. Leopard Upgrade Licenses. If you have purchased an Upgrade for Mac OS X Leopard license, then subject to the terms and conditions of this License, you are granted a limited non-exclusive license to install, use and run one (1) copy of the Apple Software on a single Apple-branded computer as long as that computer has a properly licensed copy of Mac OS X Leopard already installed on it. If you have purchased a Family Pack Upgrade for Mac OS X Leopard license, then subject to the terms and conditions of this License, you are granted a limited non-exclusive license to install, use and run one (1) copy of the Apple Software on up to a maximum of five (5) Apple-branded computers at a time as long as those computers are located in the same household (as defined above), are used by persons who occupy that same household, and each such computer has a properly licensed copy of Mac OS X Leopard already installed on it. The Family Pack Upgrade for Mac OS X Leopard License does not extend to business or commercial users.to the terms and conditions of this License, you are granted a limited non-exclusive license to install, use and run one (1) copy of the Apple Software on up to a maximum of five (5) Apple-branded computers at a time as long as those computers are located in the same household (as defined above), are used by persons who occupy that same household, and each such computer has a properly licensed copy of Mac OS X Leopard already installed on it. The Family Pack Upgrade for Mac OS X Leopard License does not extend to business or commercial users.
http://images.apple.com/legal/sla/docs/macosx106.pdf
I don't know how much clearer Apple can make it. If your a 10.4 Tiger user and you purchased the 10.6 Snow Leopard upgrade for $29, you're in violation of Apple's EULA.
Just because Apple didn't force an upgrade check or some other preventable measure, doesn't excuse the EULA violation.
Whether you care or not, is up to you.
End of story.