Well, you are using funds that haven't confirmed and spending them.
The Bitcoin.org client (e.g., Bitcoin-Qt) won't let you do that but some other clients (like Blockchain.info/wallet) give you more rope with which to hang yourself.
And [Edit: one of] your transactions attempting to spend those previously spent funds now will never confirm. And as such your
transactions [edit: one transaction] will eventually disappear as if they were never made.
But also what will disappear are the double spend transactions that were sent to you.
If those came from SatoshiDICE, then they will eventually send a replacement payment.
[Edit: One of those two transactions you listed (70c99e6609730a8782c4b7a0fd3f27229d623abb473b42efee39b3e3953ce50b) has confirmations, so the other (b07b875e687891f4b9a1efab802ee08e5c869e3368fc3ab9f753f1fd7432a819) is the only one that has a parent which is a double spend.
As far as why 16a58f5eaa5c4750403e7ca505b4d84832a9041ba414ce7e67b056d325e927c9 isn't confirming, that isn't because of a double spend. Instead it is probably because it is "spam-like". There are "dust amounts" in it (e.g., below 0.01 BTC), the total size is over 10KB, and it probably spends funds that were just recently confirmed (i.e., in the past day). A higher fee might have helped get that in a block sooner. Using the "Custom" feature of Blockchain.info/wallet and choosing coins that have confirmations would have been another method to avoid this (or use the Bitcoin.org client and this probably would never have happened in the first place.) ]
tl;dr: What do you do now? You wait for some miner to include 16a58f5eaa5c4750403e7ca505b4d84832a9041ba414ce7e67b056d325e927c9 in a block -- it could be up to a day or so. And you stop messing around with SatoshiDICE using the same wallet that you use for payments in which you want transactions to confirm in a timely manner.
