While it's down, we can't send or receive Steem or SBD. This is also why our web site temporarily doesn't show the option for buying/selling Steem and SBD. These options will automatically reappear as soon as we have the wallet back up again.
We're working as fast as possible to get the wallet back up. In the worst case, I expect it to be up in the next two to three hours.
If you've reused an existing memo to buy or sell Steem/SBD, your transaction will automatically be processed at the time our Steem wallet comes back online.