The short answer is, if used correctly, Lock Pages In Memory can enhance SQL Server performance on 64-bit systems.
The long answer has us taking a few steps back.
First of all, you need to understand that there is a difference between paging and paging to disk. With modern operating systems, ALL memory is allocated in pages within the VAS (Virtual Address Space). This is not a bad thing, this is how it works.
There are two problems with the way SQL Server works with buffer pool memory when Lock Pages is not used:
First, it is more expensive to allocate memory. When a process starts or asks for more memory, the OS creates new pages for it on demand. So, normally, as SQL Server runs it will be requesting, getting, freeing pages by chatting with the OS all the time, which is expensive.
Second, NUMA doesn't work very well. Proper NUMA support means that the application can count on a page being resident in physical memory that is the closest to the processor the thread is on, but when the OS is taking over the paging, SQL Server can't guarantee that. It has to check for NUMA residency for each page request, which is expensive as well.
When you enable Lock Pages in Memory, SQL Server doesn't have to deal with either of these issues for the buffer pool because it uses the AWE API for memory management.
Firstly, when it asks for memory, it does so only once, and gets a list of pages from the OS all at once. Then, in the future, it can allocate these pages as it needs to without having to ask the OS for them.
Secondly, because it is locking the pages from the OS, it knows that the properties of these pages won't change. So if the page is a NUMA page, it will put it in the NUMA Buffer Pool and not have to worry about verifying that it is in NUMA the next time it checks.
You will notice these improvements both as the database ramps up (when memory allocation would happen), and also over time (when normally SQL Server would be dealing with the OS for page allocation/deallocation).
If you want further details, there is an excellent technical article on this by Slava Oks's, when he was on the SQL Server team. He also has a Q&A post on the topic another great article on how NUMA works in SQL Server.