Depends really on if you'll be satisfied with using online word processors like Google Docs, because Sony removed the ability to install Linux on the PS3 (so much for their "It only does everything" campaign... No PS2 or Linux support) in a recent firmware revision.
And I have yet to really try out how well the PS3 web browser works, so it may not even be capable of rendering sites like Google Docs.
I honestly think you'd be better served by a cheap desktop system, or possibly a netbook, and then a separate bluray player.
i'm in the market for an inexpensive home computer [a laptop that will rarely leave the house]primarily for email, facebook, surfing the net, and some word processing [$500 - $700 range]. but i've also wanted a blue ray player to add to our excellent home theater for awhile now. last month the movie rental store around the corner closed, so thinking about getting netflix. it occurred to me today that even though we have an xbox 360, a ps3 with a keyboard might be do everything we need - including streaming netflix. any thoughts on using a ps3 as a home computer would be welcome.