I just got my Motorola Xoom Wifi only a few days ago, one of the reasons that I bought it is because I want to read ebooks (pdf, chm...) on it so I spent a huge amount of time getting Adobe Reader on it. Obviously it's not on the Android market since this is a Honeycomb device, so I tried appbrain, now I can see Adobe Reader but Xoom still refuses to install it. I also tried to install a few free pdf readers but none of them actually shows the pdf nicely. When I almost gave up, I saw that Adobe actully put the Adobe Reader for Android on their FTP server, et voila...

ftp://ftp.adobe.com/pub/adobe/reader/android/10.x/10.0.1/

I downloaded the apk file, do a "adb install AdobeReader.apk"  the next moment I can see my pdfs are nicely displayed on my Xoom :)