Here are some links & guidelines:
http://www.google.com/search?q=when+can+a+child+be+in+a+t...
http://www.google.com/search?hl=en&client=firefox-a&a...
http://www.google.com/search?hl=en&client=firefox-a&a...
If you really have to, I would opt for a mattress on the floor. We have done that as well, when my girl was younger and then at 2 years old or so, we got her her own real bed. Even with toddler rails on a "bed"...they can and do climb out or fall out.
But please do look at the links and guidelines... there are concerns addressed and general safety guidelines, in addition to "opinions."
You also need to address maturity level, motor coordination, and appropriateness for a 1 year old... if moving him to a toddler bed. Not all children or 1 year olds are the same... also factor in "transition time" for him, if you do change him into a "bed"... sometimes this can take even a couple of months for a very young child to get used to.....they will not just stay put. Even 2-3 year olds commonly will not stay put in their beds...hence sleep problems. Also, it will not only change their sleep/nap routine, it will change yours...because you will be needing to run interference in the interim that they are "adjusting" to the "bed." For example, in a bed, unlike a crib, there are no tall railings to keep them contained...thus, when putting them down to sleep or nap... they will very often just NOT stay in the bed. It may/will take longer to have them actually fall asleep etc. That's why... a crib... is cool...because it keeps them contained and more prone to actually napping and sleeping IN it... not escaping it.
Also, WHERE is he going to sleep? Hopefully, not in the same room as baby? Being in the same room as baby will for sure, interfere with HIS sleep ability and would not be fair to him, and all the new expectations he will have upon him as being the "eldest" sibling all of a sudden. Just remember, that he is still a very young child...who happens to have a sibling. Let him adjust to that. All kids adjust differently.
For us, my son is 24 months old, and he is still in his crib. Sure he is completely mobile....but this is the safest for him for now, and he still sleeps very well in it and likes his crib still.
Also address with your son, the coming of the 2nd baby... being a "sibling" is a BIG change for them... and it can take time for them to adapt, sometimes even months or longer.
All the best, and congratulations!
Susan