Google Android is built on top of Linux. The Linux kernel is licensed under the GNU General Public License, Version 2. There are many companies shipping the Android platform in their smartphones, so they need to consider something very carefully.
If the Microsoft patent portfolio they are paying for includes patents that Microsoft claims are being violated by Linux, they are required to defend against those patent claims in any country where they market their Android products.
The GPL is very clear on this -- you lose your right to use GPLv2 software if you pay patent protection fees to anyone.
There is no way for the general public to know if the patent portfolio include the patents against Linux that Microsoft has claimed to have had for many years. Microsoft has never revealed those patents, but it's time to end the FUD (Fear, Uncertainty, and Doubt), and come clean about which specific patents they are talking about.
Richard Stallman was very thoughtful about the GPL. It is designed specifically to prevent patent trolls from profiting by imposing patent fees on GPL software users.
The introduction section of the license specifies:
Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all.
However, that is only the introduction. The legalese is specified by clause 7:
7. If, as a consequence of a court judgment or allegation of patent infringement or for any other reason (not limited to patent issues), conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not distribute the Program at all. For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program.
I do not know if the patent portfolios include any that are against the Linux kernel. But if they are there, the Android manufacturers are required to take the matter to court and have the patent overturned, or they lose the right to use the software at all.
Novell's right to distribute may also be in question, depending on exactly what patents they licensed from Microsoft in their deal.