Yes! The ebook format tells you what program you need to read it (I think the kindle's .azw is the only one that doesn't have a computer program), but since Baen books are offered in .pdf, .rtf and .html, there's no problem reading them on any computer.

Buying a Baen ebook gets you access to all their different filetypes for download: Palm Pilot/Mobipocket/Kindle format, Rocketbook, EPUB/Stanza, Sony LRF, RTF and MS Reader.